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Sample records for alane alh3 nanoparticles

  1. Watching the dehydrogenation of alane (AlH3) in a TEM

    NASA Astrophysics Data System (ADS)

    Beattie, Shane; Humphries, Terry; Weaver, Louise; McGrady, Sean

    2008-03-01

    Alane (AlH3) is a promising candidate for on-board hydrogen storage applications. Its theoretical gravimetric capacity is 10.1 percent and decomposition is achieved with modest heating (60-200 deg C). We studied the dehydrogenation of alane, insitu, in a TEM. Alane powder was loaded into the TEM and heated at 80 deg C. We were able to `watch' the dehydrogenation of the alane to aluminum. Electron diffraction and dark fiend images are used to show how and where the aluminum crystallites grow. Although crystalline aluminum phases were successfully identified, some of the sample remained amorphous. We will discuss the nature of the amorphous material and present images clearly identifying the nature of the aluminum crystallites.

  2. Formation of Al2H7- anions--indirect evidence of volatile AlH3 on sodium alanate using solid-state NMR spectroscopy.

    PubMed

    Felderhoff, Michael; Zibrowius, Bodo

    2011-10-14

    After more than a decade of intense research on NaAlH(4) doped with transition metals as hydrogen storage material, the actual mechanism of the decomposition and rehydrogenation reaction is still unclear. Early on, monomeric AlH(3) was named as a possible transport shuttle for aluminium, but never observed experimentally. Here we report for the first time the trapping of volatile AlH(3) produced during the decomposition of undoped NaAlH(4) by an adduct of sodium alanate and crown ether. The resulting Al(2)H(7)(-) anion was identified by solid-state (27)Al NMR spectroscopy. Based on this indirect evidence of volatile alane, we present a simple description of the processes occurring during the reversible dehydrogenation of NaAlH(4).

  3. A structural study of bis-(trimethylamine)alane, AlH 3·2NMe 3, by variable temperature X-ray crystallography and DFT calculations

    NASA Astrophysics Data System (ADS)

    Humphries, Terry D.; Sirsch, Peter; Decken, Andreas; Sean McGrady, G.

    2009-04-01

    The structure of AlH 3·2NMe 3 has been investigated by single-crystal X-ray diffraction over the range of 296-173 K. Over this temperature range a phase change is observed from Cmca to Pbcm where the methyl groups convert from a statistically disordered conformation to adopt a mutually eclipsed conformation at lower temperatures. Measurement of the unit cell dimensions shows a decrease in the lengths of the a and b axes, and an increase in that of the c axis as the temperature is lowered, with inflections apparent between 223 and 233 K in the region of the phase change. Low-temperature DSC measurements reveal the change from Pbcm to Cmca to occur at 218.3 K, with an enthalpy of 107.7 J mol -1. The molecular structure of AlH 3·2NMe 3 is compared with those of related amine adducts of Group 13 hydrides, either measured experimentally or calculated using DFT methods. 1H, 13C and 27Al NMR spectroscopy has also been utilized to characterize AlH 3·2NMe 3 and its 1:1 counterpart AlH 3·NMe 3.

  4. Electrical conductivity of aluminum hydride AlH3 at high pressure and temperature

    NASA Astrophysics Data System (ADS)

    Shakhray, Denis; Molodets, Alexander; Fortov, Vladimir; Khrapak, Aleksei

    2009-06-01

    A study of electrophysical and thermodynamic properties of alane AlH3 under multi shock compression has been carried out. The increase in specific electroconductivity of alane at shock compression up to pressure 100 GPa have been measured. High pressures and temperatures were obtained with explosive device, which accelerates the stainless impactor up to 3 km/sec. The impact shock is split into a shock wave reverberating in alane between two stiff metal anvils. The conductivity of shocked alane increases in the range up to 60-75 GPa and is about 30 1/Ohm*cm. In this region the semiconductor regime is true for shocked alane. The conductivity of alane achieves approximately 500 1/Ohm*cm at 80-90 GPa. In this region conductivity is interpreted in frames of the conception of the ``dielectric catastrophe'', taking into consideration significant difference between electronic states of isolated AlH3 molecule and condensed alane.

  5. Doping of AlH3 with alkali metal hydrides for enhanced decomposition kinetics

    NASA Astrophysics Data System (ADS)

    Sandrock, Gary; Reilly, James

    2005-03-01

    Aluminum hydride, AlH3, has inherently high gravimetric and volumetric properties for onboard vehiclular hydrogen storage (10 wt% H2 and 0.148 kg H2/L). Yet it has been widely neglected because of its kinetic limitations for low-temperature H2 desorption and the thermodynamic difficulties associated with recharging. This paper considers a scenario whereby doped AlH3 is decomposed onboard and recharged offboard. In particular, we show that particle size control and doping with small levels of alkali metal hydrides (e.g., LiH) results in accelerated H2 desorption rates nearly high enough to supply fuel-cell and ICE vehicles. The mechanism of enhanced H2 desorption is associated with the formation of alanate windows (e.g., LiAlH4) between the AlH3 particles and the external gas phase. These alanate windows can be doped with Ti to further enhance transparency, even to the point of accomplishing slow decomposition of AlH3 at room temperature. It is highly likely 2010 gravimetric and volumetric vehicular system targets (6 wt% H2 and 0.045 kg/L) can be met with AlH3. But a new, low-cost method of offboard regeneration of spent Al back to AlH3 is yet needed.

  6. Metallization of aluminum hydride AlH3 at high multiple-shock pressures

    NASA Astrophysics Data System (ADS)

    Molodets, A. M.; Shakhray, D. V.; Khrapak, A. G.; Fortov, V. E.

    2009-05-01

    A study of electrophysical and thermodynamic properties of alane AlH3 under multishock compression has been carried out. The increase in specific electroconductivity of alane at shock compression up to pressure 100 GPa has been measured. High pressures and temperatures were obtained with an explosive device, which accelerates the stainless impactor up to 3 km/s. A strong shock wave is generated on impact with a holder containing alane. The impact shock is split into a shock wave reverberating in alane between two stiff metal anvils. This compression loads the alane sample by a multishock manner up to pressure 80-90 GPa, heats alane to the temperature of about 1500-2000 K, and lasts 1μs . The conductivity of shocked alane increases in the range up to 60-75 GPa and is about 30(Ωcm)-1 . In this region the semiconductor regime is true for shocked alane. The conductivity of alane achieves approximately 500(Ωcm)-1 at 80-90 GPa. In this region, conductivity is interpreted in frames of the conception of the “dielectric catastrophe,” taking into consideration significant differences between the electronic states of isolated molecule AlH3 and condensed alane.

  7. Unexpected acidity enhancement triggered by AlH3 association to phosphines.

    PubMed

    Martín-Sómer, Ana; Lamsabhi, Al Mokhtar; Mó, Otilia; Yáñez, Manuel

    2012-06-28

    The complexes formed by the interaction between a series of phosphines R-PH(2) (R = H, CH(3), c-C(3)H(5), C(6)H(5)) and AlH(3) have been investigated through the use of high-level G4 ab initio calculations. These very stable complexes behave as much stronger acids than the isolated phosphines. This dramatic acidity enhancement, which can be as high as 174 kJ mol(-1), results from a much greater stabilization of the anionic deprotonated species with respect to the neutral one, upon AlH(3) association. This effect depends quantitatively on the nature of the substituent R and is smaller for R = C(6)H(5) because of the conjugation of the P lone pair with the aromatic system. More unexpectedly, however, the phosphine-alane complexes, RPH(2):AlH(3), are more acidic than the corresponding phosphine-borane RPH(2):BH(3) analogues. This unexpected result is due to the enhanced stability of the anionic deprotonated species for complexes involving AlH(3), because the delocalization of the newly created P lone pair with the P-Al bonding density is more favorable when the Lewis acid is aluminum trihydride than when it is borane.

  8. Density Functional Studies of NaAlH_4, NaH and AlH_3

    NASA Astrophysics Data System (ADS)

    Aguayo, Aaron; Singh, David J.

    2004-03-01

    We report electronic structure investigations of the bonding of the alanate NaAlH4 and the related materials NaH and AlH_3. The results are based on density functional calculations using the LAPW method. All three compounds are insulators. AlH3 has a substantially covalent electronic structure with a band gap of approximately 2 eV, while NaAlH4 and NaH both show larger band gaps of approximately 4 eV and are much more ionic. This ionic character is stabilized by the Madelung energy in the respective crystal structures. We discuss the implications for H storage.

  9. Decomposition kinetics of the AlH3 polymorphs.

    PubMed

    Graetz, Jason; Reilly, James J

    2005-12-01

    Aluminum hydride polymorphs (alpha-AlH3, beta-AlH3, and gamma-AlH3) were prepared by organometallic synthesis. Hydrogen capacities approaching 10 wt % at desorption temperatures less than 100 degrees C have been demonstrated with freshly prepared AlH3. The temperature-dependent rate constants were determined by measuring the isothermal hydrogen evolution between 60 degrees C and 140 degrees C. Fractional decomposition curves showed good fits using both the second and third-order Avrami-Erofeyev equations, indicating that the decomposition kinetics are controlled by nucleation and growth of the aluminum phase in two and three dimensions. The large activation energies measured for the AlH3 polymorphs suggest that the decomposition occurs via an activated complex mechanism with complexes consisting of approximately nine AlH3 molecules (1-2 unit cells for alpha-AlH3).

  10. Trapped H2 in AlH3

    NASA Astrophysics Data System (ADS)

    Conradi, Mark; Senadheera, Lasitha; Carl, Erik; Ivancic, T. M.; Bowman, R. C., Jr.; Hwang, S. J.; Udovic, T. J.

    2007-03-01

    Trapped molecular hydrogen has been discussed for years in H-storage systems such as NaAlH4. Here we report proton NMR and neutron vibration spectroscopy (NVS) evidence for H2 in AlH3 samples. In static sample NMR, a sharp line appears on top of the broad AlH3 solid signal. MAS further sharpens this line and identifies it as H2 by its chemical shift. Upon cooling, the line broadens and disappears near 20K, confirming the H2 identification. NVS reports energy-gain peaks at the H2 rotational energy (J=1 to 0).

  11. Point-defect-mediated dehydrogenation of AlH3

    NASA Astrophysics Data System (ADS)

    Ismer, Lars; Janotti, Anderson; Van de Walle, Chris G.

    2010-11-01

    Based on hybrid density functional calculations, we propose a microscopic mechanism for the dehydrogenation of AlH3. Our results indicate that mass transport mediated by positively charged hydrogen vacancies (VH+) is likely the rate-limiting mechanism. The calculated activation energy of 1.72 eV is in good agreement with experimental values. The high formation energy and hence low concentration of VH+ explains why AlH3 does not decompose at room temperature, although it is thermodynamically unstable. Issues of maintaining charge neutrality are addressed.

  12. Alanes formation on the Al(111) surface

    NASA Astrophysics Data System (ADS)

    Rangan, Sylvie; Veyan, Jean-Francois; Chabal, Yves J.; Chaudhuri, Santanu; Muckerman, James T.

    2008-03-01

    Alane clusters (AlxHy) are believed to be the ubiquitous intermediates in hydrogen storage reactions for a wide variety of alanates (LiAlH4, NaAlH4) currently considered for hydrogen storage. The formation and behavior of alanes at surfaces appear to control and limit the efficiency of hydrogen storage. In particular, hydrogen adsorption on the Al(111) surface leads to the coexistence of several adsorbed species, the concentration of which is affected by the step density, the surface coverage and the temperature. We combine density functional theory (DFT) and surface infra-red (IR) absorption spectroscopy to uncover the mechanisms for alane formation on Al(111) surfaces. At low coverage, DFT predicts a two-fold bridge site adsorption for atomic hydrogen, consistent with previous Electron Energy Loss Spectroscopy measurements. At higher coverage, the formation of small chemisorbed AlH3 occurs at the step edges. With increasing coverage AlH3 is extracted from the step edge and becomes highly mobile on the terraces in a weakly bound state. This mobility is the key factor leading to the growth of larger alanes through AlH3 oligomerization. For these large alanes, previous Thermal Programmed Desorption studies are discussed and compared to the thermal stability observed in IR.

  13. Combustion of Alane and Aluminum with Water for Hydrogen and Thermal Energy Generation

    DTIC Science & Technology

    2010-01-01

    17–24]. Alane is a covalently bonded hydride which often appears in a polymeric form ( AlH3 )n and has at least seven known non- solvated forms. The...most stable polymorph is a- AlH3 [19,25,26]. Alane decomposition or dehy- drogenation (an endothermic process) has been found to be dependent on particle...Steady-state and one-dimensional approxi- mations are invoked. The entire region of interest is divided into six zones: (1) Al/ AlH3 -ice preheat zone

  14. Surface changes on AlH3 during the hydrogen desorption

    NASA Astrophysics Data System (ADS)

    Kato, Shunsuke; Bielmann, Michael; Ikeda, Kazutaka; Orimo, Shin-ichi; Borgschulte, Andreas; Züttel, Andreas

    2010-02-01

    Surface change of α-AlH3 during the hydrogen desorption was investigated by means of in situ x-ray photoelectron spectroscopy combined with thermal desorption spectroscopy. The surface of AlH3 covered by an oxide layer significantly changes upon hydrogen desorption and the hydrogen desorption rate increases remarkably. In this study, the role of the surface oxide layer on AlH3 in view of the hydrogen desorption kinetics was investigated. AlH3 only decomposes into Al and H2 at the free surface and not in the bulk. Therefore, a closed surface oxide layer prevents the thermodynamically unstable AlH3 from decomposition.

  15. Pressure induced band gap opening of AlH3

    NASA Astrophysics Data System (ADS)

    Geshi, Masaaki; Fukazawa, Taro

    2013-02-01

    Pressure-induced band gap opening (PIBGO) of AlH3 with a Pm3barn structure is verified by using first-principles calculations. With increasing pressure, the semimetallic band structures change to the indirect band gap semiconducting band structure at about 300 GPa. The key points of this phenomenon are (1) the moderately large difference of electronegativity between aluminium and hydrogen and (2) the orthogonality between the 3s states and 2s states of Al. We have been confirmed that the structure is stable up to and including 500 GPa resulting from the structural relaxation and phonon calculations. The band gap is more accurately confirmed by GW calculations than done by DFT-GGA ones. The band gap may open at about 200 GPa. This phenomenon may be verified by means of a leading-edge experimental technique.

  16. Accelerated thermal decomposition of AlH3 for hydrogen-fueled vehicles

    NASA Astrophysics Data System (ADS)

    Sandrock, G.; Reilly, J.; Graetz, J.; Zhou, W.-M.; Johnson, J.; Wegrzyn, J.

    2005-02-01

    The potential for using aluminum hydride, AlH3, for vehicular hydrogen storage is explored. It is shown that particle-size control and doping of AlH3 with small levels of alkali-metal hydrides (e.g. LiH) results in accelerated desorption rates. For AlH3 20 mol % LiH, 100 °C desorption kinetics are nearly high enough to supply vehicles. It is highly likely that 2010 gravimetric and volumetric vehicular system targets (6 wt % H2 and 0.045 kg/L) can be met with onboard AlH3. However, a new, low-cost method of off-board regeneration of spent Al back to AlH3 is needed.

  17. Formation and bonding of alane clusters on Al(111) surfaces studied by infrared absorption spectroscopy and theoretical modeling.

    PubMed

    Chaudhuri, Santanu; Rangan, Sylvie; Veyan, Jean-Francois; Muckerman, James T; Chabal, Yves J

    2008-08-13

    Alanes are believed to be the mass transport intermediate in many hydrogen storage reactions and thus important for understanding rehydrogenation kinetics for alanates and AlH3. Combining density functional theory (DFT) and surface infrared (IR) spectroscopy, we provide atomistic details about the formation of alanes on the Al(111) surface, a model environment for the rehydrogenation reactions. At low coverage, DFT predicts a 2-fold bridge site adsorption for atomic hydrogen at 1150 cm(-1), which is too weak to be detected by IR but was previously observed in electron energy loss spectroscopy. At higher coverage, steps are the most favorable adsorption sites for atomic H adsorption, and it is likely that the AlH3 molecules form (initially strongly bound to steps) at saturation. With increasing exposures AlH3 is extracted from the step edge and becomes highly mobile on the terraces in a weakly bound state, accounting for step etching observed in previous STM studies. The mobility of these weakly bound AlH3 molecules is the key factor leading to the growth of larger alanes through AlH3 oligomerization. The subsequent decomposition and desorption of alanes is also investigated and compared to previous temperature programmed desorption studies.

  18. Development and Test of a Highly Energetic AlH3 Difluoramino Propellant.

    DTIC Science & Technology

    The object of this program was to combine the difluoramine binder with the AlH3 to produce a propellant having high theoretical impulse and high...shelf life of the TVOPA/ AlH3 propellants. Stripping of an inert diluent at 140F for 16 hours reduced the gassing rate and improved the shelf life...markedly. Using this mix process with a more stable AlH3 , a shelf life of 5 years for large web grains stored at 70 F may be feasible. In process hazards

  19. Dynamical stability of the cubic metallic phase of AlH3 at ambient pressure

    NASA Astrophysics Data System (ADS)

    Kim, Duck Young; Scheicher, Ralph H.; Ahuja, Rajeev

    2009-03-01

    We have characterized the high-pressure cubic phase of AlH3 using density functional theory to determine mechanical as well as electronic properties and lattice dynamics from the response function method [1]. Metallization in AlH3 under pressure has been studied, which is of great interest not only from a fundamental physics point of view for the study of phenomena related to metallic hydrogen, but also, because metallic AlH3 possesses weaker Al-H bonds than other insulating phases [2]. Our phonon calculations show the softening of a particular mode with decreasing pressure, indicating the onset of a dynamical instability that continues to persist at ambient conditions. We find from analyzing the atomic and electronic interactions using theoretical calculations that finite-temperature effects lead to the desired stabilization of metallic AlH3 at ambient conditions.[0pt] [1] PRB 78, 100102(R) (2008). [0pt] [2] APL 92, 201903 (2008).

  20. Catalytic effect of Ti and Ni on dehydrogenation of AlH3: A first principles investigation

    NASA Astrophysics Data System (ADS)

    Yu, H. Z.; Dai, J. H.; Song, Y.

    2015-08-01

    Ab initio calculations were performed for the M-doped (M = Ti or Ni) AlH3 to investigate influence of dopants Ti and Ni on the dehydrogenation properties of AlH3. It was found that Ti and Ni prefer to substitute for Al atom in both the bulk phase and the slab surface. However a large amount of energy was needed for Ni to dope into AlH3 making that Ni might not a suitable catalyst for AlH3. Mechanisms that Ti improved the dehydrogenation properties of AlH3 were clarified. Ti greatly decreased the dehydrogenation energy of AlH3 by weakening the interaction between Al and H atoms, its influence on the dehydrogenation of AlH3 was however sensitive to the occupation behavior. The calculations indicated that the catalytic effect of Ti was weaker if Ti substitutes for Al than its interstitial occupation.

  1. Hydrogen release from systems containing phosphine, borane, alane and galane: A mechanistic study

    NASA Astrophysics Data System (ADS)

    Nguyen, Vinh Son; Majumdar, D.; Leszczynski, Jerzy; Nguyen, Minh Tho

    2013-10-01

    The H2 release mechanism from phosphine borane and phosphine alane was investigated using quantum chemical methods (MP2/aug-cc-pVTZ geometry optimization and coupled-cluster energies were obtained through complete basis set extrapolation, CCSD(T)/CBS). The effect of catalysts borane, alane and galane on the processes was also explored. As the energy barriers for the release of H2 from BH3PH3 and AlH3PH3 are much higher than the B-P and Al-P bond energies, the presence of inherent catalysts can reduce substantially such energy barriers (using BH3 for BH3PH3, while AlH3 and GaH3 for AlH3PH3), and these systems could be useful as probable hydrogen source.

  2. Calculations suggest facile hydrogen release from water using boranes and alanes as catalysts

    NASA Astrophysics Data System (ADS)

    Swinnen, Saartje; Nguyen, Vinh Son; Sakai, Shogo; Nguyen, Minh Tho

    2009-04-01

    Producing H 2 from water is a very challenging task. Using quantum chemical calculations with the MP2 and CCSD(T) methods and the aug-cc-pVnZ basis sets (extrapolated to CBS), we investigated the possibilities of B 2H 6, AlH 3, Al 2H 6 and AlH 3BH 3 to act as catalysts in the reactions that split water. Hydrogen production from H 2O is greatly accelerated in the presence of alane, dialane or borane-alane in such a way that reaction H 2O + Al 2H 6 is a nearly spontaneous process. The main catalytic effect of AlH 3 arises from the occurrence of a strong dihydrogen bond of the type Al-H δ-- δ+H-O within a cyclic transition structure.

  3. Mechanistic models for LAH reductions of acetonitrile and malononitrile. Aggregation effects of Li+ and AlH3 on imide-enamide equilibria.

    PubMed

    Glaser, Rainer; Ulmer, Laura; Coyle, Stephanie

    2013-02-01

    The results are reported of an ab initio study of the addition of LiAlH(4) to acetonitrile and malononitrile at the MP2(full)/6-311+G* level considering the effects of electron correlation at higher levels up to QCISD(T)/6-311++G(2df,2pd) and including ether solvation. All imide (RCH(2)CH═N(-)) and enamide (RCH(-)CH═NH ↔ RCH═CHN(-)H) adducts feature strong interactions between the organic anion and both Li(+) and AlH(3). The relative stabilities of the tautomeric LAH adducts are compared to the tautomer preference energies of the LiH adducts and of the hydride adducts of the nitriles. Alane affinities were determined for the lithium ion pairs formed by LiH addition to the nitriles. The results show that alane binding greatly affects the imide-enamide equilibria and that alane complexation might even provide a thermodynamic preference for the imide intermediate. While lithium enamides of malononitrile are much more stable than lithium imides, alane binding dramatically reduces the enamide preference so that both tautomers are present at equilibrium. Implications are discussed regarding to the propensity for multiple hydride reductions and with regard to the mechanism of reductive nitrile dimerization. A detailed mechanism is proposed for the formation of 2-aminonicotinonitrile (2ANN) in the LAH reduction of malononitrile.

  4. First-principles study of structural stabilities of AlH3 under high pressure

    NASA Astrophysics Data System (ADS)

    Feng, Wenxia; Cui, Shouxin; Feng, Min

    2014-07-01

    The structural stabilities and electronic properties of AlH3 under high pressure are investigated by using the plane-wave pseudopotential method. Our results demonstrate that the sequence of the pressure-induced phase transition is Fd 3 bar m(β) → cmcm(α ') → R 3 bar c(α) → Pnma(hp 1) → Pm 3 bar n(hp 2), and the transition pressures are 0.49, 0.91, 47, and 70 GPa, respectively. Im 3 bar m , Pnnm(γ) and P63/m structures are not stable in the 0-100 GPa. β, α ', α, and hp1 structures of AlH3 are nonmetals, while Pm 3 bar n structure of AlH3 is metallic, and the pressure-induced metallization is ascribed to phase transition under higher compression.

  5. SHEPARD, ALAN

    NASA Image and Video Library

    1961-01-01

    S61-03850 (1 Oct. 1961) --- Astronaut Alan B. Shepard Jr. (right) receives a plaque and award from members of the British Rocket Society. Photo credit: NASA or National Aeronautics and Space Administration

  6. Electron band structure of the high pressure cubic phase of AlH3

    NASA Astrophysics Data System (ADS)

    Shi, Hongliang; Zarifi, Niliffar; Yim, Wai-Leung; Tse, J. S.

    2012-07-01

    The electronic band structure of the cubic Pm3n phase of AlH3 stable above 100 GPa is examined with semi-local, Tran-Blaha modified Becke-Johnson local density approximation (TB-mBJLDA), screened hybrid density functionals and GW methods. The shift of the conduction band to higher energy with increasing pressure is predicted by all methods. However, there are significant differences in detail band structure. In the pressure range from 90 to160 GPa, semi-local, hybrid functional and TB-mBJLDA calculations predicted that AlH3 is a poor metal. In comparison, GW calculations show a gap opening at 160 GPa and AlH3 becomes a small gap semi-conductor. From the trends of the calculated band shifts, it can be concluded that the favourable conditions leading to the nesting of Fermi surfaces predicted by semi-local calculation have disappeared if the exchange term is included. The results highlight the importance of the correction to the exchange energy on the band structure of hydrogen dominant dense metal hydrides at high pressure hydrides and may help to rationalize the absence of superconductivity in AlH3 from experimental measurements.

  7. Lewis base complexes of AlH3: prediction of preferred structure and stoichiometry.

    PubMed

    Humphries, Terry D; Munroe, Keelie T; Decken, Andreas; McGrady, G Sean

    2013-05-21

    The structures adopted by a range of complexes AlH3·nL, (n = 1 or 2), have been explored in detail to identify the factors that determine the value of n, and whether a monomeric or dimeric arrangement is preferred for the 1 : 1 complexes. Single-crystal X-ray diffraction, vibrational and NMR spectroscopies, and thermal analysis data have been collected, DFT calculations have been performed for AlH3·nL species, and pK(a) values have been collated for a series of amine and phosphine ligands L. The pK(a) of the ligand L exerts an important influence on the type of complex formed: as the basicity of L increases, a monomeric structure is favoured over a dimeric arrangement. Dimeric amine complexes form if pK(a) < 9.76, while monomeric complexes are preferred when pK(a) > 9.99. The steric requirements of L also influence the structural preference: bulky ligands with large cone angles (>163°) tend to favour formation of monomers, while smaller cone angles (<125°) encourage the formation of dimeric or 1 : 2 adducts. The steric bulk of the ligand appears to be more important for phosphine complexes, with smaller phosphines being unable to stabilise the complex at ambient temperatures even through dimerisation. Raman spectroscopy and DFT calculations have been particularly helpful in elucidating the stoichiometric preferences of complexes that have been contentious; these include AlH3·NMe2Et, AlH3·NMe3 and AlH3·nEt2O.

  8. Stability of ferromagnetic phase in Fe-doped AlH3

    NASA Astrophysics Data System (ADS)

    Nisar, J.; Scheicher, R. H.; Peng, X.; Ahuja, R.

    2009-03-01

    We have carried out a systematic theoretical investigation of Fe-doped AlH3 to study its magnetic properties and to assess the stability of the ferromagnetic phase in this material. All calculations were performed using the projector augmented-wave method and generalized-gradient approximation (GGA) as well as GGA+U. The magnetic moment is found to be constant at 1.1 μB per Fe-atom in the ferromagnetic configuration for distances between adjacent Fe atoms varying from 3.25 Å to 7.41 Å. We conclude that the ferromagnetic phase in Fe-doped AlH3 is stable both for near and far configurations of Fe. The stability of the ferromagnetic phase is due to the holes created by Fe-doping and the larger level splitting of the interacting gap states within the ferromagnetic phase.

  9. Kinetics of hydrogen desorption from MgH2 and AlH3 hydrides

    NASA Astrophysics Data System (ADS)

    Terent'ev, P. B.; Gerasimov, E. G.; Mushnikov, N. V.; Uimin, M. A.; Maikov, V. V.; Gaviko, V. S.; Golovatenko, V. D.

    2015-12-01

    Kinetic parameters of the process of thermal decomposition of the MgH2 hydride (obtained by the method of the mechanoactivation of magnesium in a hydrogen atmosphere) and of the commercial AlH3 hydride have been studied upon the rapid heating in the range of temperatures of 150-510°C at hydrogen pressures of 0-2 atm. The time dependences of the amount of hydrogen released by the metal hydrides at different temperatures and pressures have been determined. It has been shown that the activation energies of the hydrogen desorption are 135 kJ/mol for MgH2 and 107 kJ/mol for AlH3. The maximum rates of hydrogen desorption from the investigated metal hydrides have been established, and the temperatures and initial pressures that ensure the maximum rate and maximum volume of the hydrogen release have been determined.

  10. AlH3 and Al2H6: Magic Clusters with Unmagical Properties

    NASA Astrophysics Data System (ADS)

    Rao, B. K.; Jena, P.; Burkart, S.; Ganteför, G.; Seifert, G.

    2001-01-01

    Enhanced stability, low electron affinity, and high ionization potential are the hallmarks of a ``magic'' cluster. With an electron affinity of 0.28 eV, ionization potential of 11.43 eV, and a large binding energy, AlH3 satisfies these criteria. However, unlike other magic clusters that interact only weakly with each other, two AlH3 clusters bind to each other with an energy of 1.54 eV. The resulting Al2H6, while also a magic cluster in its own right, possesses the most unusual property that the difference between its adiabatic and vertical detachment energy is about 2 eV-the largest of any known cluster. These results, based on density functional theory, are verified experimentally through photodetachment spectroscopy.

  11. Undamped low-energy plasmon in AlH3 at high pressure

    NASA Astrophysics Data System (ADS)

    Gurtubay, I. G.; Rousseau, B.; Bergara, A.

    2010-08-01

    Pressure strongly modifies electronic and optical properties of solids. In this work we report ab initio time-dependent density-functional theory calculations of the dielectric response of the high-pressure metallic phase of aluminum hydride (AlH3) within the random-phase approximation. Besides the conventional free-electronlike plasmon, which is highly damped, low-energy transitions between states near the Fermi level that appear in this metallized phase give rise to a low-energy undamped collective mode. This feature is expected to induce an abrupt edge in the experimentally measured reflectivity just below 1 eV and also affect electronic correlations close to the Fermi energy. Our work shows that AlH3 is basically a hydrogen sublattice weakly perturbed by Al atoms.

  12. Point-defect-mediated dehydrogenation of alane

    NASA Astrophysics Data System (ADS)

    Ismer, Lars

    2011-03-01

    For the engineering of better hydrogen storage materials a systematic understanding of their hydrogen sorption kinetics is crucial. Theoretical studies on metal hydrides have indicated that in many cases point defects control mass transport and hence hydrogen uptake and release. Manipulating point-defect concentrations thus allows control over hydrogen sorption kinetics, opening up new engineering strategies. However, in some cases the relevance of kinetic limitations due to point defects is still under debate; kinetic inhibition of hydrogen sorption has also been attributed to surface effects, e.g. oxide layers or low recombination rates. We present a systematic analysis of the dehydrogenation kinetics of alane (AlH3), one of the prime candidate materials for hydrogen storage. Using hybrid-density functional calculations we determine the concentrations and mobilities of point defects and their complexes. Kinetic Monte Carlo simulations are used to describe the full dehydrogenation reaction. We show that under dehydrogenation conditions charged hydrogen vacancy defects form in the crystal, which have a strong tendency towards clustering. The vacancy clusters denote local nuclei of Al phase, and the growth of these nuclei eventually drives the AlH3/Al transformation. However, the low concentration of vacancy defects limits the transport of hydrogen across the bulk, and hence acts as the rate-limiting part of the process. The dehydrogenation is therefore essentially inactive at room temperature, explaining why AlH3 is metastable for years, even though it is thermodynamically unstable. Our derived activation energy and dehydrogenation curves are in excellent agreement with the experimental data, providing evidence for the relevance of bulk point-defect kinetics. Work performed in collaboration with A. Janotti and C. G. Van de Walle, and supported by DOE.

  13. First-principles prediction of low-energy structures for AlH3

    NASA Astrophysics Data System (ADS)

    Sun, Shoutian; Ke, Xuezhi; Chen, Changfeng; Tanaka, Isao

    2009-01-01

    We report density-functional calculations that predict ten different low-energy structures for aluminum hydride AlH3 with space groups Pnma , P6/mmm , I4/mcm , P4/mbm , P4/nmm , Pm3¯m , P21/m , P21/c , Pbcm , and P4/n . Phonon calculations within harmonic approximation reveal unstable modes in the P6/mmm , I4/mcm , P4/mbm , P4/nmm , Pm3¯m , P21/m , and P21/c structures, indicating that they are unstable at low temperatures. The calculations show that the thermodynamic stabilities for AlH3 with space groups Pnma , Pbcm , and P4/n are overall close to the existing α - and γ-AlH3 . From x-ray powder-diffraction patterns, the simulated main-peak positions for AlH3 (P4/n) are in good agreement with experimental δ-AlH3 . A full Rietveld analysis reveals that the fitting space groups R3¯c , Pbcm , and Pnma to the experimental x-ray powder-diffraction pattern of α-AlH3 gives almost the same satisfactory result.

  14. Novel methods for synthesizing halide-free alane without the formation of adducts

    NASA Astrophysics Data System (ADS)

    Dinh, Long V.; Knight, Douglas A.; Paskevicius, Mark; Buckley, Craig E.; Zidan, Ragaiy

    2012-04-01

    Many of the current synthesis methods for aluminum hydride (alane—AlH3) involve reacting AlCl3 and LiAlH4 in solvents. The reaction requires the formation of an alane adduct such as AlH3ṡ[(C2H5)2O] prior to obtaining crystallized stable α-AlH3. This process requires several hours of pumping in a vacuum system to remove the ether and convert the alane etherate into stable α-alane. This crystallization process is both costly and hazardous because a large amount of highly flammable material (e.g. ether) is removed by vacuum pumps over several hours. Conversely, the work presented herein describes novel methods to synthesize adduct-free alane. It is demonstrated here that AlH3 can form by mixing AlCl3 and LiAlH4 in the solid state and heating to 75∘C; only α-AlH3 was obtained. The α-AlH3 product can be washed with minimal solvents leading to zero formation of alane adducts. In addition, the unwanted LiCl by-product is also removed during the solvent wash, resulting in halide-free α-alane. Although simply mixing and heating the reactants led to a 40% yield of alane, having the reactants compacted and mechanically pressed while heating increases the yield to 60% crystalline α-AlH3.

  15. Theoretical study of the vibrational properties of NaAlH4 with AlH3 vacancies.

    PubMed

    Zhang, Feng; Wang, Yan; Chou, M Y

    2011-01-01

    It has been suggested that the diffusion of AlH3 vacancies plays an essential role in the decomposition of NaAlH4, a prototypical material for hydrogen storage. We find from first-principles calculations that the AlH3 vacancy induces several isolated vibrational modes that are highly localized in the vacancy region with frequencies within the phonon gaps of pure NaAlH4 in both the alpha and gamma phases. Thus, the proposed existence of AlH3 vacancies in the dehydrogenation reaction of NaAlH4 can be possibly confirmed with the experimental detection of these unique vibrational modes associated with the AlH3 vacancy.

  16. The catalyzed hydrogen sorption mechanism in alkali alanates.

    PubMed

    Kocabas Atakli, Züleyha Özlem; Callini, Elsa; Kato, Shunsuke; Mauron, Philippe; Orimo, Shin-Ichi; Züttel, Andreas

    2015-08-28

    The hydrogen sorption pathways of alkali alanates were analyzed and a mechanism for the catalytic hydrogen sorption was developed. Gibbs free energy values of selected intermediate steps were calculated based on experimentally determined thermodynamic data (enthalpies and entropies) of individual hydrides: MAlH4, M3AlH6, and MH. The values of the activation energies, based on the intermediates M(+), H(-), MH, and AlH3, were obtained. The mechanism of the catalytic activity of Ti is finally clarified: we present an atomistic model, where MAlH4 desorbs hydrogen through the intermediates M(+), H(-), MH, and AlH3 to the hexahydride M3AlH6 and finally the elemental hydride MH. The catalyst acts as a bridge to transfer M(+) and H(-) from MAlH4(-) to the neighboring AlH4(-), forming AlH6(3-) and finally isolated MH, leaving AlH3 behind, which spontaneously desorbs hydrogen to give Al and 1.5H2. The proposed mechanism is symmetric in the direction of hydrogen desorption as well as readsorption processes.

  17. High pressure Raman and visible absorption study of AlH3

    NASA Astrophysics Data System (ADS)

    Shimura, N.; Takeichi, T.; Kume, T.; Sasaki, S.; Shimizu, H.; Ohmura, A.; Ikeda, K.; Nakamori, Y.; Orimo, S.

    2010-03-01

    Raman and visible absorption spectra of AlH3 were measured at high pressures in order to clarify the structural and electronic phase transitions. For the Raman results, abrupt decrease in Raman intensity was found at 30 GPa, implying that there exists a structural transition from the α phase to higher pressure phase. Correspondingly, the spectral change in the optical absorption was observed at almost the same pressure of 30 GPa. From the absorption measurements, the band gap is expected to close at the pressure higher than 50 GPa.

  18. Phonon, IR, and Raman spectra, NMR parameters, and elastic constant calculations for AlH3 polymorphs.

    PubMed

    Vajeeston, P; Ravindran, P; Fjellvåg, H

    2011-10-06

    The electronic structure, lattice dynamics, and mechanical properties of AlH(3) phases have been studied by density functional calculations. The chemical bonding in different polymorphs of AlH(3) are evaluated on the basis of electronic structures, charge density analysis, and atomic charges, as well as bond overlap population analysis and the Born effective charges. The phonon dispersion relations and phonon density of states of all the polymorphs of AlH(3) are calculated by direct force-constant method. Application of pressure induces seqauence of phase transitions in β-AlH(3) which are understood from the phonon dispersive curves of the involved phases. The previously predicted phases (Chem. Mater. 2008, 20, 5997) are found to be dynamically stable. The calculated single crystal elastic constants reveal that all the studied AlH(3) polymorphs are easily compressible. The chemical bonding of these polymorphs have noticeable covalent character (except the hp2 phase) according to the present chemical bonding analyses. For all these polymorphs, the NMR-related parameters, such as isotropic chemical shielding, quadrupolar coupling constant, and quadrupolar asymmetry, are also calculated. All IR- and Raman-active phonon frequencies, as well as the corresponding intensities, are calculated for all the AlH(3) polymorphs and are compared with available experimental results.

  19. In situ X-ray diffraction measurement of the hydrogenation and dehydrogenation of aluminum and characterization of the recovered AlH3

    NASA Astrophysics Data System (ADS)

    Saitoh, H.; Sakurai, Y.; Machida, A.; Katayama, Y.; Aoki, K.

    2010-03-01

    Pristine aluminum was hydrogenated to form AlH3 at 8.9 GPa and 600 °C. The cyclic formation and decomposition of the hydride were measured by in situ synchrotron X-ray diffraction measurement. AlH3 synthesized under high pressure and temperature was recovered at ambient conditions. The recovered AlH3 was characterized by conventional powder X-ray diffraction measurement and Raman spectroscopy. The results of the characterization were consistent with that obtained for chemically prepared AlH3 and indicated that single phase α-AlH3 was obtained.

  20. Dehydriding reaction of AlH3: in situ microscopic observations combined with thermal and surface analyses

    NASA Astrophysics Data System (ADS)

    Ikeda, K.; Muto, S.; Tatsumi, K.; Menjo, M.; Kato, S.; Bielmann, M.; Züttel, A.; Jensen, C. M.; Orimo, S.

    2009-05-01

    The dehydriding reaction of single-phase α- AlH3 was investigated by in situ microscopic observations combined with thermal and surface analyses. Before the dehydriding reaction, primary AlH3 particles of size 100 nm-1 µm were thought to be covered by an oxide layer with a thickness of less than 5 nm. Both the precipitation/grain-growth of metallic Al of size 1-50 nm and an increase in 'boundary space' were clearly observed inside the particles, while the morphologies of the particles covered by the layer did not change during the dehydriding reaction. This preliminary report provides fundamental information for a further study of AlH3 as a possible hydrogen storage material.

  1. Dehydriding reaction of AlH3: in situ microscopic observations combined with thermal and surface analyses.

    PubMed

    Ikeda, K; Muto, S; Tatsumi, K; Menjo, M; Kato, S; Bielmann, M; Züttel, A; Jensen, C M; Orimo, S

    2009-05-20

    The dehydriding reaction of single-phase alpha- AlH3 was investigated by in situ microscopic observations combined with thermal and surface analyses. Before the dehydriding reaction, primary AlH3 particles of size 100 nm-1 microm were thought to be covered by an oxide layer with a thickness of less than 5 nm. Both the precipitation/grain-growth of metallic Al of size 1-50 nm and an increase in 'boundary space' were clearly observed inside the particles, while the morphologies of the particles covered by the layer did not change during the dehydriding reaction. This preliminary report provides fundamental information for a further study of AlH3 as a possible hydrogen storage material.

  2. Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

    DOE PAGES

    Wang, Lin -Lin; Herwadkar, Aditi; Reich, Jason M.; ...

    2016-08-18

    Here, alane (AlH3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters formmore » primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.« less

  3. Towards Direct Synthesis of Alane: A Predicted Defect-Mediated Pathway Confirmed Experimentally.

    PubMed

    Wang, Lin-Lin; Herwadkar, Aditi; Reich, Jason M; Johnson, Duane D; House, Stephen D; Peña-Martin, Pamela; Rockett, Angus A; Robertson, Ian M; Gupta, Shalabh; Pecharsky, Vitalij K

    2016-09-08

    Alane (AlH3 ) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2 , indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 10(4)  bar expected from bulk thermodynamics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Giant anharmonicity suppresses superconductivity in AlH3 under pressure

    NASA Astrophysics Data System (ADS)

    Rousseau, Bruno; Bergara, Aitor

    2010-09-01

    The anharmonic self-energy of two zone boundary phonons were computed to lowest order for AlH3 in the Pm3¯n structure at 110 GPa. The wave vector and branch index corresponding to these modes are situated in a region of phase space providing most of the electron-phonon coupling. The self-energies are found to be very large and the anharmonic contribution to the linewidth of one of the modes studied could be distinguished from the electron-phonon linewidth. It is found that anharmonicity suppresses the electron-phonon coupling parameter λ , providing a possible explanation for the disagreement between experiment and previous theoretical studies of superconductivity in this system.

  5. pardInvestigation of the Direct Hydrogenation of Aluminum to Alane in Supercritical Fluids

    NASA Astrophysics Data System (ADS)

    Jensen, Craig; McGrady, Sean; Ayabe, Reyna; Reddy, Ben

    2007-03-01

    Alane, AlH3 has many of the properties that are requisite for materials to be considered viable for onboard hydrogen storage applications. Most notibly, it contains 10.1 wt% hydrogen and undergoes dehydrogenation at appreciable rates at temperatures below 100^oC. However, the very low, >= 6 kJ/mol, enthalpy of dehydrogenation of AlH3 prohibits subsequent re-hydrogenation through standard gas-solid techniques except at very high pressures or very low temperatures. The extremely low solubility of gaseous H2 in conventional organic solvents also vitiates a solution-based approach. Re-hydrogenation of Al using a supercritical fluid potentially offers a workable approach since the fluid can act as a solvent, at the same time remaining completely miscible with permanent gases like hydrogen. Recently, it has been found that mixtures of NaH and Al can be hydrogenated to sodium alanate, NaAlH4 under modest pressures and temperatures in supercritical fluids. We have now extended these studies to the hydrogenation of Al to AlH3. The results of these studies and experimental details will be reported.

  6. Volume dependence of AlH3 band gap at high pressures

    NASA Astrophysics Data System (ADS)

    Shakhray, D. V.; Golyshev, A. A.; Kim, V. V.; Molodets, A. M.; Fortov, V. E.

    2011-06-01

    The volume dependence of the band gap for aluminum hydride (alane) is compared at high static and dynamic pressures. Room temperature high pressure isotherm data and multiple-shock conductivity data were used for the reconstruction of the volume dependence of the alane band gap in the pressure range 50-75 GPa. The traditional exponential relationship for the temperature dependence of semiconductor conductivity with the power law volume dependence of the aluminum hydride band gap is suggested in the regions of volumes 11.5-12.5 cm3/mol, pressures 50-75 GPa and temperatures 1270-1370 K.

  7. Chemical Bonding of AlH3 Hydride by Al-L2,3 Electron Energy-Loss Spectra and First-Principles Calculations

    PubMed Central

    Tatsumi, Kazuyoshi; Muto, Shunsuke; Ikeda, Kazutaka; Orimo, Shin-Ichi

    2012-01-01

    In a previous study, we used transmission electron microscopy and electron energy-loss (EEL) spectroscopy to investigate dehydrogenation of AlH3 particles. In the present study, we systematically examine differences in the chemical bonding states of Al-containing compounds (including AlH3) by comparing their Al-L2,3 EEL spectra. The spectral chemical shift and the fine peak structure of the spectra were consistent with the degree of covalent bonding of Al. This finding will be useful for future nanoscale analysis of AlH3 dehydrogenation toward the cell. PMID:28816996

  8. Ultra-low diffusion barriers for the AlH3-related vacancies in γ-NaAlH4

    NASA Astrophysics Data System (ADS)

    Zhang, Feng; Wang, Yan; Chou, Mei-Yin

    2011-03-01

    It has been suggested that the diffusion of AlH3 -related vacancies plays an essential role in the decomposition of NaAlH4 , a prototypical material for hydrogen storage[1,2]. We find from first-principles calculations that the diffusion barrier for both the neutral AlH3 vacancy and the charged AlH4- vacancy in the newly proposed γ -phase of NaAlH4 is only about 0.1 eV, much lower than the barrier for the diffusion of corresponding vacancies in the conventional α -phase 0.5 eV, calculated with the same method. Possible schemes to facilitate the α --> γ phase transformation in order to improve the kinetics of the decomposition reaction of NaAlH4 will also be discussed.

  9. A density functional theory study of the one-dimensional alane

    NASA Astrophysics Data System (ADS)

    Cui, Yan-Hong; Wang, Jian-Guo; Xu, W.

    2010-01-01

    The AlH1-6, Al2H1-7, Al3H1-9, AlmH3m (m = 4-10), and the periodic helical structure of the one-dimensional (1D) alane are studied by means of density functional theory calculations. The helical isolated structure is more stable than those in the corresponding cyclic and other geometries. A new periodic 1D helical alane structure is predicted for the first time. The stability of this periodic 1D helical alane structure has been confirmed by its large average binding energy based on AlH3, large energy gap of highest occupied molecular orbital and lowest unoccupied molecular orbital, and the typically double helical π-orbital which parallels its bone structure.

  10. A density functional theory study of the one-dimensional alane.

    PubMed

    Cui, Yan-Hong; Wang, Jian-Guo; Xu, W

    2010-01-15

    The AlH(1-6), Al(2)H(1-7), Al(3)H(1-9), Al(m)H(3m) (m = 4-10), and the periodic helical structure of the one-dimensional (1D) alane are studied by means of density functional theory calculations. The helical isolated structure is more stable than those in the corresponding cyclic and other geometries. A new periodic 1D helical alane structure is predicted for the first time. The stability of this periodic 1D helical alane structure has been confirmed by its large average binding energy based on AlH(3), large energy gap of highest occupied molecular orbital and lowest unoccupied molecular orbital, and the typically double helical pi-orbital which parallels its bone structure.

  11. Elastic, superconducting, and thermodynamic properties of the cubic metallic phase of AlH3 via first-principles calculations

    NASA Astrophysics Data System (ADS)

    Wei, Yong-Kai; Ge, Ni-Na; Ji, Guang-Fu; Chen, Xiang-Rong; Cai, Ling-Cang; Zhou, Su-Qin; Wei, Dong-Qing

    2013-09-01

    The lattice dynamic, elastic, superconducting, and thermodynamic properties of the high-pressure cubic metallic phase AlH3 are studied within density function theory. The calculated elastic modulus and phonon dispersion curves at various pressures indicate that the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature was calculated using Allen-Dynes modification of the McMillan formula based on the Bardeen-Cooper-Schrieffer theory. It is found that Tc approaches a linear decrease in the low pressure range at the rate dTC/dP ≈-0.22 K/GPa but gradually decreases exponentially at higher pressure, and then it becomes 0 K upon further compression. The calculations indicate that Tc is about 2.042 K at 110 GPa, in agreement with experimental results. The soft phonon modes, especially the lowest acoustic mode, contribute almost 79% to the total electron-phonon coupling parameter sλ for cubic AlH3 at 73 GPa. However, they disappear gradually with increasing pressure, showing a responsibility for the variation of Tc. The thermodynamic properties of cubic AlH3, such as the dependence of thermal expansion coefficient αV on pressure and temperature, the specific heat capacity CP, as well as the electronic specific heat coefficient Cel, were also investigated by the quasi-harmonic approximation theory.

  12. Theoretical study of the vibrational properties of NaAlH4 with AlH3 vacancies

    NASA Astrophysics Data System (ADS)

    Chou, Mei-Yin; Zhang, Feng; Wang, Yan

    2011-03-01

    We investigate from first-principles calculations the vibrational properties in the presence of the AlH3 vacancy in both α and γ phases of NaAlH4 . When AlH3 is removed from an AlH4- anion, the remaining H recombines with another neighboring AlH4- anion and forms an AlH52 - unit with slightly deformed D3 h symmetry. For both α - and γ -NaAlH4 , the AlH3 vacancy induces several isolated phonon modes that are highly localized on the AlH52 - unit with frequencies within the band gap separating the Al-H stretching modes and Al-H bending modes in pure NaAlH4 . Similar localized phonon modes also exist in the gap separating the Al-H bending modes and the modes involving the rotation of AlH4- anions for the γ phase. On the other hand, for both α and γ phases of NaAlH4 with charged AlH4- vacancies, no isolated phonon modes were found to be localized in the vacancy region with frequencies within the band gap of the pure crystal. These theoretical findings suggest further experimental studies to identify the defects that are involved in the decomposition of NaAlH4 .

  13. Photoelectron spectroscopy of the aluminum hydride anions: AlH2-, AlH3-, Al2H6-, Al3H9-, and Al4H12-

    NASA Astrophysics Data System (ADS)

    Zhang, Xinxing; Wang, Haopeng; Collins, Evan; Lim, Alane; Ganteför, Gerd; Kiran, Boggavarapu; Schnöckel, Hansgeorg; Eichhorn, Bryan; Bowen, Kit

    2013-03-01

    We report measurements of the negative ion photoelectron spectra of the simple aluminum hydride anions: AlH2-, AlH3-, Al2H6-, Al3H9-, and Al4H12-. From these spectra, we measured the vertical detachment energies of the anions, and we estimated the electron affinities of their neutral counterparts. Our results for AlH2-, AlH3-, and Al2H6- were also compared with previous predictions by theory.

  14. Photoelectron spectroscopy of the aluminum hydride anions: AlH2(-), AlH3(-), Al2H6(-), Al3H9(-), and Al4H12(-).

    PubMed

    Zhang, Xinxing; Wang, Haopeng; Collins, Evan; Lim, Alane; Ganteför, Gerd; Kiran, Boggavarapu; Schnöckel, Hansgeorg; Eichhorn, Bryan; Bowen, Kit

    2013-03-28

    We report measurements of the negative ion photoelectron spectra of the simple aluminum hydride anions: AlH2(-), AlH3(-), Al2H6(-), Al3H9(-), and Al4H12(-). From these spectra, we measured the vertical detachment energies of the anions, and we estimated the electron affinities of their neutral counterparts. Our results for AlH2(-), AlH3(-), and Al2H6(-) were also compared with previous predictions by theory.

  15. Vacancy-mediated dehydrogenation of sodium alanate

    PubMed Central

    Gunaydin, Hakan; Houk, Kendall N.; Ozoliņš, Vidvuds

    2008-01-01

    Clarification of the mechanisms of hydrogen release and uptake in transition-metal-doped sodium alanate, NaAlH4, a prototypical high-density complex hydride, has fundamental importance for the development of improved hydrogen-storage materials. In this and most other modern hydrogen-storage materials, H2 release and uptake are accompanied by long-range diffusion of metal species. Using first-principles density-functional theory calculations, we have determined that the activation energy for Al mass transport via AlH3 vacancies is Q = 85 kJ/mol·H2, which is in excellent agreement with experimentally measured activation energies in Ti-catalyzed NaAlH4. The activation energy for an alternate decomposition mechanism via NaH vacancies is found to be significantly higher: Q = 112 kJ/mol·H2. Our results suggest that bulk diffusion of Al species is the rate-limiting step in the dehydrogenation of Ti-doped samples of NaAlH4 and that the much higher activation energies measured for uncatalyzed samples are controlled by other processes, such as breaking up of AlH4− complexes, formation/dissociation of H2 molecules, and/or nucleation of the product phases. PMID:18299582

  16. Growth of aluminum on Si using dimethyl-ethyl amine alane

    NASA Astrophysics Data System (ADS)

    Neo, Yoichiro; Niwano, Michio; Mimura, Hidenori; Yokoo, Kuniyoshi

    1999-04-01

    The paper describes growth of aluminum on a hydrogen terminated Si (100) surface using dimethyl-ethyl amine alane. The growth rate depends on the substrate temperature with an activation energy of 0.56 eV at the temperature ranging from 150 to 250°C. Selective growth of Al into 1.5-μm diameter via-holes is successfully demonstrated at the substrate temperature of 150°C. In situ FTIR measurements suggest that growth of Al occurs by the chemical reaction between AlH 3 and a hydrogen terminated Si surface.

  17. Regeneration of AlH3 studied with Raman and Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lacina, David; Wegrzyn, J.; Reilly, J. J.; Graetz, Jason

    2010-03-01

    Aluminum hydride compounds are known to exhibit a 10% by weight hydrogen storage capacity that makes them suited for technologies that require hydrogen as a fuel. The current challenge associated with this material is how to regenerate the hydride from the spent fuel and H2 gas. We employ a two-step process to regenerate the hydride compound which first requires the formation of a stable aluminum hydride adduct using a tertiary amine. This is followed by a second step consisting of adduct separation and hydride recovery, involving transamination to create a less stable adduct. We present results which show that alane-amines can be formed by hydrogenation of catalyzed aluminum in a solvent at low pressures using one of several tertiary amines. Raman and infrared spectroscopy was performed on the products of these reactions to better understand the structure of the alane amines that are formed, as well as the hydrogenation reactions that take place. A vibrational analysis of the regeneration products performed with Raman and infrared spectroscopy is presented and will help clarify the molecular and vibrational structures of these alane amine adducts.

  18. Lewis base complexes of AlH3: structural determination of monomeric and polymeric adducts by X-ray crystallography and DFT calculations.

    PubMed

    Humphries, Terry D; Munroe, Keelie T; Decken, Andreas; McGrady, G Sean

    2013-05-21

    The AlH3 adducts of TMEDA (Me2NCH2CH2NMe2), DIOX (O(CH2CH2)2O), TEA (Et3N), BDMA (PhNMe2), and TMPDA (Me2NCH2CH2CH2NMe2) have each been characterised by single-crystal X-ray diffraction at low temperature, by (1)H, (14)N and (27)Al NMR and FT-Raman and FT-IR spectroscopy, and by DFT calculations and elemental analysis. Hence, AlH3·TMEDA and AlH3·DIOX are both shown to adopt a polymeric structure, with the bidentate ligand bridging two Al centres, each of which adopts a trigonal bipyramidal (TBP) arrangement with equatorial hydride moieties. The 1 : 2 adduct AlH3·2BDMA is monomeric but the geometry at the Al centre resembles closely that of the polymeric TMEDA and DIOX complexes. AlH3·TEA alone adopts a monomeric structure in which the Al centre is tetrahedrally coordinated by three hydride and one amine ligand. The Al-L bond distance of 2.0240(17) Å for AlH3·TEA is the shortest of all the complexes in this study, and AlH3·TEA also possesses the shortest Al-H bonds. AlH3·DIOX has the shortest Al-L bond distance of the polymeric species (2.107(14) Å) on account of the higher electronegativity of the oxygen donor. The structure of AlH3·TMEDA was determined at low temperature (monoclinic space group P2(1)/c), and salient features are compared to the previous room temperature study, for which a highly disordered orthorhombic space group (P2(1)2(1)2(1)) was reported. The polymeric structures appear to be stabilised by a number of intermolecular interactions and unconventional hydrogen bonds; these are most pronounced for AlH3·DIOX, whose chains are connected by highly directional C-H···H-Al bonding with an H···H distance of 2.32(6) Å.

  19. Dry mechanochemical synthesis of alane from LiH and AlCl3.

    PubMed

    Hlova, Ihor Z; Gupta, Shalabh; Goldston, Jennifer F; Kobayashi, Takeshi; Pruski, Marek; Pecharsky, Vitalij K

    2014-01-01

    A mechanochemical process for the synthesis of alane (AlH3) starting from lithium hydride (LiH) and aluminium chloride (AlCl3) at room temperature and the underlying reaction pathway have been studied. In contrast to a conventional process using the same two reactants dissolved in diethyl ether, our approach enables a solvent-free synthesis, thereby directly leading to adduct-free alane. The method described here is quick and efficient, resulting in the quantitative conversion of all aluminium in the starting mixture to alane. Both the intermediate compounds formed during the reaction and the final products have been characterized by powder X-ray diffraction, solid-state (27)Al NMR spectroscopy, and temperature programmed desorption analysis of the as-milled mixtures. We show that excess LiH in the starting mixture (with an optimal ratio of 9LiH : 1AlCl3) is essential for the formation and stability of Al-H bonds, initially in the form of alanates and, eventually, as alane. Further processing of this mixture, gradually adding AlCl3 to reach the ideal 3LiH : 1AlCl3 stoichiometry, appears to restrict the local accumulation of AlCl3 during the ball-milling process, thereby preventing the formation of unstable intermediates that decompose to metallic Al and molecular hydrogen. We also demonstrate that under the milling conditions used, a moderate hydrogen pressure of ca. 300 bar is required to suppress competing reactions that lead to the formation of metallic Al at room temperature. The identification of the reaction intermediates at each stage of the synthesis provides significant insight into the mechanism of this solid-state reaction, which may potentially afford a more rational approach toward the production of AlH3 in a simple solvent-free process.

  20. Alan Bean Art Exhibit

    NASA Image and Video Library

    2009-07-19

    NASA Apollo 12 Astronaut and Artist Alan Bean gives remarks at the opening of the exhibit "Alan Bean: Painting Apollo, First Artist on Another World" at the National Air and Space Museum, Monday, July 20, 2009 in Washington. The show opening coincided with the 40th anniversary celebration of Apollo. Photo Credit: (NASA/Bill Ingalls)

  1. Alan Bean Art Exhibit

    NASA Image and Video Library

    2009-07-19

    Guest view works of art by NASA Apollo 12 Astronaut and Artist Alan Bean during the opening of the show "Alan Bean: Painting Apollo, First Artist on Another World" at the National Air and Space Museum, Monday, July 20, 2009 in Washington. The show opening coincided with the 40th anniversary celebration of Apollo. Photo Credit: (NASA/Bill Ingalls)

  2. Dynamical stability of the cubic metallic phase of AlH3 at ambient pressure: Density functional calculations

    NASA Astrophysics Data System (ADS)

    Kim, D. Y.; Scheicher, R. H.; Ahuja, R.

    2008-09-01

    We have characterized the high-pressure cubic phase of AlH3 from ab initio using density functional theory to determine mechanical as well as electronic properties and lattice dynamics (phonon-dispersion relations) from the response function method. Our zero-temperature phonon calculations show the softening of a particular mode with decreasing pressure, indicating the onset of a dynamic instability that continues to persist at ambient conditions. This instability can, however, be removed when finite electronic temperature effects are considered in the calculations. We furthermore identify a particular momentum transfer in the phonon-dispersion relation, matching a corresponding momentum transfer in the electronic band structure.

  3. Alane adsorption and dissociation on the Si(0 0 1) surface

    NASA Astrophysics Data System (ADS)

    Smith, R. L.; Bowler, D. R.

    2017-10-01

    We used DFT to study the energetics of the decomposition of alane, AlH3, on the Si(0 0 1) surface, as the acceptor complement to PH3. Alane forms a dative bond with the raised atoms of silicon surface dimers, via the Si atom lone pair. We calculated the energies of various structures along the pathway of successive dehydrogenation events following adsorption: AlH2, AlH and Al, finding a gradual, significant decrease in energy. For each stage, we analyse the structure and bonding, and present simulated STM images of the lowest energy structures. Finally, we find that the energy of Al atoms incorporated into the surface, ejecting a Si atom, is comparable to Al adatoms. These findings show that Al incorporation is likely to be as precisely controlled as P incorporation, if slightly less easy to achieve.

  4. Alane adsorption and dissociation on the Si(0 0 1) surface.

    PubMed

    Smith, R L; Bowler, D R

    2017-10-04

    We used DFT to study the energetics of the decomposition of alane, AlH3, on the Si(0 0 1) surface, as the acceptor complement to PH3. Alane forms a dative bond with the raised atoms of silicon surface dimers, via the Si atom lone pair. We calculated the energies of various structures along the pathway of successive dehydrogenation events following adsorption: AlH2, AlH and Al, finding a gradual, significant decrease in energy. For each stage, we analyse the structure and bonding, and present simulated STM images of the lowest energy structures. Finally, we find that the energy of Al atoms incorporated into the surface, ejecting a Si atom, is comparable to Al adatoms. These findings show that Al incorporation is likely to be as precisely controlled as P incorporation, if slightly less easy to achieve.

  5. ASTRONAUT SHEPARD, ALAN - TX

    NASA Image and Video Library

    1963-03-07

    Astronaut Alan Shepard with Gilruth, and Astronauts Slayton, Cooper, Carpenter, Schirra, Grissom around the Manned Spacecraft Center (MSC) sign at the Farnsworth-Chambers Bldg. FARNSWORTH-CHAMBERS BLDG., HOUSTON, TX B&W

  6. Alan Bean Art Exhibit

    NASA Image and Video Library

    2009-07-19

    NASA Apollo 7 Astronaut Walt Cunningham, left, and NASA STS-125 Mission Specialist Michael Massimino talk with another guest during the opening of "Alan Bean: Painting Apollo, First Artist on Another World" by NASA Apollo 12 Astronaut and Artist Alan Bean at the National Air and Space Museum, Monday, July 20, 2009 in Washington. The show opening coincided with the 40th anniversary celebration of Apollo. Photo Credit: (NASA/Bill Ingalls)

  7. Defect-mediated Alane formation on Ti-doped Al(111) surfaces: a DFT study

    NASA Astrophysics Data System (ADS)

    Herwadkar, Aditi; Wang, Lin-Lin; Johnson, Duane D.

    2011-03-01

    Understanding of Alane (AlH3) formation on Al surface remains elusive, including interpreting STM results under various conditions. Using density functional theory calculations, we study Alane formation on close-packed (111) and stepped surfaces with {111} and {100} microfacets of Al, with and without Ti as a catalyst. We find that Ti dopants act as catalyst in the formation of Alane on Al(111) via a vacancy-mediated mechanism. Additionally, we find the Alane formation energy at steps is 40 % less than that from the flat surface. We assess the energetics of various surface-defect configurations to understand the concerted roles that Ti dopants, surface vacancies, and step defects play in Alane formation. Work was supported in part by Department of Energy, Office of Basic Energy Science under contract DEFC36-05GO15064 (Sandia Metal-Hydride Center of Excellence), DE-FG02-03ER15476, DE-FG02-03ER46026, and DE-AC02-07CH11358 at the Ames Laboratory operated by Iowa State University.

  8. A benign synthesis of alane by the composition-controlled mechanochemical reaction of sodium hydride and aluminum chloride

    DOE PAGES

    Hlova, Ihor; Goldston, Jennifer F.; Gupta, Shalabh; ...

    2017-05-30

    Solid-state mechanochemical synthesis of alane (AlH3) starting from sodium hydride (NaH) and aluminum chloride (AlCl3) has been achieved at room temperature. The transformation pathway of this solid-state reaction was controlled by a stepwise addition of AlCl3 to the initial reaction mixture that contained sodium hydride in excess of stoichiometric amount. As in the case of previously investigated LiH–AlCl3 system, complete selectivity was achieved whereby formation of unwanted elemental aluminum was fully suppressed, and AlH3 was obtained in quantitative yield. Reaction progress during each step was investigated by means of solid-state NMR and powder X-ray diffraction, which revealed that the overallmore » reaction proceeds through a series of intermediate alanates that may be partially chlorinated. The NaH–AlCl3 system presents some subtle differences compared to LiH–AlCl3 system particularly with respect to optimal concentrations needed during one of the reaction stages. Based on the results, we postulate that high local concentrations of NaH may stabilize chlorine-containing derivatives and prevent decomposition into elemental aluminum with hydrogen evolution. As a result, complete conversion with quantitative yield of alane was confirmed by both SSNMR and hydrogen desorption analysis.« less

  9. Temperature behavior of the AlH3 polymorph by in situ investigation using high resolution Raman scattering.

    PubMed

    Giannasi, A; Colognesi, D; Fichtner, M; Röhm, E; Ulivi, L; Ziparo, C; Zoppi, M

    2011-02-10

    A Raman investigation of the AlH(3) polymorph has been carried out at a low temperature (20 K) under helium atmosphere (2 bar). The pristine material was composed of three polymorphs, namely, the α, β, and γ phases. The β phase has been removed by warming the sample to 70 °C, while further heating at 100 °C was used to remove the γ phase. This allowed us to evidence, on a purely experimental basis, the characteristic Raman spectrum for each phase. Raman spectra, for the three phases, have been also calculated using density functional theory, and the results have been compared to the present experimental data, allowing for a univocal assignment, to each phase, of its characteristic spectral features.

  10. Multiscale modelling of Interaction of Alane Clusters on Al(111) surface: A Reactive Force Field and Infrared Absorption Spectroscopy Approach

    NASA Astrophysics Data System (ADS)

    Ojwang, Julius; van Duin, Adri; Goddard, William, III; van Santen, Rutger

    2010-10-01

    Alanes are believed to be the ubiquitous facilitators of mass transport of aluminum atoms during the thermal decomposition of NaAlH4. Alanes also take part on decomposition of AlH3, another important material for hydrogen storage. We have used interplay of theoretical simulations (reactive force field and density functional theory) and experiments (IR reflection absorption spectroscopy) to address the issue of the role of alanes as facilitators of mass transport of aluminum atoms. We have obtained valuable details on the mechanism of formation and agglomeration of alanes on Al(111) surface. Our simulations show that, on the Al(111) surface, alanes oligomerize into larger alanes. The identification of these string like intermediates as a precursor to the bulk hydride phase allows us to explain the loss of resolution in surface IR experiments with increasing hydrogen coverage on single crystal Al(111) surface. This is in excellent agreement with the experimental works of Go et al. (E. Go, K. Thuermer, J.E. Reutt-Robey, Surf. Sci.,437:377(1999)).

  11. Alan Bean Art Exhibit

    NASA Image and Video Library

    2009-07-19

    Former NASA Astronaut and U.S. Senator John Glenn is seen at the opening of the exhibit "Alan Bean: Painting Apollo, First Artist on Another World" at the National Air and Space Museum, Monday, July 20, 2009 in Washington. The show opening coincided with the 40th anniversary celebration of Apollo. Photo Credit: (NASA/Carla Cioffi)

  12. Intrinsic and mechanically modified thermal stabilities of α-, β- and γ-aluminum trihydrides AlH3

    NASA Astrophysics Data System (ADS)

    Orimo, S.; Nakamori, Y.; Kato, T.; Brown, C.; Jensen, C. M.

    2006-04-01

    The intrinsic and mechanically modified thermal stabilities of the α-, β-, and γ-phases of AlH3 have been experimentally determined. The thermogravimetric profiles of the α- and γ-phases exhibit dehydriding reactions in the temperature range of 370 450 K. The amounts of hydrogen released are nearly 9 mass %. The profile of the β-phase shows the continuous dehydriding reactions, which differs from the other two phases. The values of the enthalpy of dehydriding reactions ΔHdehyd. are determined to be 6.0±1.5, -3˜-5 and 1.0±0.5 kJ/mol H2 for the α-, β- and γ-phases, respectively. The milling-time dependences of the powder X-ray diffraction measurement and thermal analyses indicate the occurrence of the dehydriding reactions both in the α- and γ-phases during milling, but there is no drastic change in the β-phase.

  13. Initial gas phase reactions between Al(CH3)3/AlH3 and ammonia: theoretical study.

    PubMed

    Lisovenko, Anna S; Morokuma, Keiji; Timoshkin, Alexey Y

    2015-01-29

    Mechanisms of initial stages of gas phase reactions between trimethylaluminum and ammonia have been explored by DFT studies. Subsequent substitution of CH3 groups in AlMe3 by amido groups and substitution of hydrogen atoms in ammonia by AlMe2 groups have been considered. Structures of Al(CH3)x(NH2)3-x, NHx(Al(CH3)2)3-x (x = 0-3) and related donor-acceptor complexes, dimerization products, and reaction pathways for the methane elimination have been obtained. The transition state for the first methane elimination from Al(CH3)3NH3 adduct is the highest point on the reaction pathway; subsequent processes are exothermic and do not require additional activation energy. In excess ammonia, subsequent methane elimination reactions may lead to formation of [Al(NH2)3]2, while in excess trimethylaluminum, formation of N(AlMe2)3 is feasible. Formation of [AlMe2NH2]2 dimer is very favorable thermodynamically. Studies on model reactions between AlH3 and NH3 indicate that reaction barriers obtained for hydrogen-substituted species may serve as an upper estimate in studying the reactivity of methyl-substituted analogues in more complex systems.

  14. Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

    PubMed Central

    2011-01-01

    Knowledge of the relative stabilities of alane (AlH3) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH3−nRn (R = Me, Et; n = 0−3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH2−nRn (R = Me, Et; n = 0−2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine−alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of ΔG° for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system. PMID:22962624

  15. Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation.

    PubMed

    Wong, Bryan M; Lacina, David; Nielsen, Ida M B; Graetz, Jason; Allendorf, Mark D

    2011-04-21

    Knowledge of the relative stabilities of alane (AlH(3)) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH(3-n)R(n) (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH(2-n)R(n) (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of ΔG° for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.

  16. Preparation of monopodal and bipodal aluminum surface species by selective protonolysis of highly reactive [AlH3(NMe2Et)] on silica.

    PubMed

    Sauter, D W; Chiari, V; Aykac, N; Bouaouli, S; Perrin, L; Delevoye, L; Gauvin, R M; Szeto, K C; Boisson, C; Taoufik, M

    2017-09-12

    The synthesis and characterization of silica-grafted monopodal and bipodal aluminum hydrides has been achieved starting from 200 °C- and 700 °C-annealed silica and [AlH3(NMe2Et)]. The mechanism by which aluminum trishydride reacts with isolated and vicinal silanols, assisted by the amine, has been investigated computationally at the ωB97XD-DFT level.

  17. Al-H σ-bond coordination: expanded ring carbene adducts of AlH3 as neutral bi- and tri-functional donor ligands.

    PubMed

    Abdalla, Joseph A B; Riddlestone, Ian M; Tirfoin, Remi; Phillips, Nicholas; Bates, Joshua I; Aldridge, Simon

    2013-06-21

    Thermally robust expanded ring carbene adducts of AlH3 have been synthesized with a view to probing their ligating abilities via Al-H σ-bond coordination. While κ(2) binding to the 14-electron [Mo(CO)4] fragment is readily demonstrated, interaction with [Mo(CO)3] results in μ:κ(1),κ(1) and μ:κ(2),κ(2) bridging linkages rather than terminal κ(3) binding.

  18. Reaction kinetics for the solid state synthesis of the AlH3/MgCl2 nano-composite by mechanical milling.

    PubMed

    Duan, C W; Hu, L X; Sun, Y; Zhou, H P; Yu, H

    2015-09-14

    The process of mechanical milling has been proved to be a cost-effective way to synthesize the AlH3/MgCl2 nano-composite by using MgH2 and AlCl3 as reagents. However, so far there is no comprehensive knowledge of the kinetics of this process. In an effort to predict the reaction progress and optimize the milling parameters, the kinetics of the synthesis of the AlH3/MgCl2 nano-composite by mechanical milling of MgH2 and AlCl3 is experimentally investigated in the present work. The reaction progress or the transformation fraction upon milling for different times is evaluated using the isothermal hydrogen desorption test of the as-milled samples at 220 °C, which is much lower than the threshold temperature for the de-hydriding of the reagent MgH2 but enough for the de-hydriding of the as-synthesized nano-sized AlH3. The effects of milling parameters on the reaction kinetics as well as the underlying mechanism are discussed by referring to the mechanical energy input intensity, the vial temperature and the Gibbs free energy change for the reaction. Furthermore, it is found that the Johnson-Mehl-Avrami (JMA) model can well describe the kinetics theoretically. By fitting the experimental data with the JMA expression, the theoretical kinetics expressions, the equation parameters, and the activation energy are obtained.

  19. ASTRONAUT SHEPARD, ALAN - CAPE

    NASA Image and Video Library

    1961-05-05

    S61-01927 (5 May 1961) --- Mercury-Redstone 3 (MR-3), the United States' first manned spaceflight, is launched from Cape Canaveral on a suborbital mission. Astronaut Alan B. Shepard Jr. was the pilot of the Mercury spacecraft, designated "Freedom 7". The spacecraft attained a maximum speed of 5,180 miles per hour (mph), reached an altitude of 116 1/2 statute miles, and landed 302 statute miles downrange from Cape Canaveral, Florida. Photo credit: NASA or National Aeronautics and Space Administration

  20. Addition of ammonia to AlH3 and BH3. Why does only aluminum form 2:1 adducts?

    PubMed

    Czerw, M; Goldman, A S; Krogh-Jespersen, K

    2000-01-24

    The electronic structures of the mono- and bisammonia adducts EH3NH3 and EH3(NH3)2, E = B and Al, have been investigated using ab initio electronic structure methods. Geometries were optimized at the MP2/cc-pVTZ level. Higher-level correlated methods (MP4(SDTQ), QCISD(T), CCSD(T)), as well as the G2 and CBS-Q methods, were used to obtain accurate bond dissociation energies. The E-N bond dissociation energy (De) is computed near 33 kcal/mol (E = B) and 31 kca/mol (E = Al), respectively. Whereas the Al-N bond energy pertaining to the second ammonia molecule in AlH3(NH3)2 is 11-12 kcal/mol, only a transition-state structure may be located for the species BH3(NH3)2. We analyze factors which may distinguish Al from B with respect to the formation of stable bisamine adducts. The most significant difference relates to electronegativity and hence the propensity of boron to engage in predominantly covalent bonding, as compared with the bonding of aluminum with ammonia, which shows substantial electrostatic character. Neither steric factors nor the participation of d-orbitals is found to play an important role in differentiating aluminum from boron. The lesser electronegativity of third-row elements appears to be the critical common feature allowing the formation of hypercoordinate complexes of these elements in contrast to their second-row analogues. Consideration of some group 14 analogues and hard/soft acid/base effects supports this view.

  1. Ab initio studies on phase transition, thermoelastic, superconducting and thermodynamic properties of the compressed cubic phase of AlH3

    NASA Astrophysics Data System (ADS)

    Wei, Yong-Kai; Ge, Ni-Na; Chen, Xiang-Rong; Ji, Guang-Fu; Cai, Ling-Cang; Gu, Zhuo-Wei

    2014-03-01

    The phase transition, thermoelastic, lattice dynamic, and thermodynamic properties of the cubic metallic phase AlH3 were obtained within the density-function perturbation theory. The calculated elastic modulus and phonon dispersion curves under various pressures at 0 K indicate the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature Tc was calculated using the Allen-Dynes modification of the McMillan formula based on BCS theory. The calculations show that Tc for the cubic phase AlH3 is 8.5 K (μ*=0.1) at the onset of this phase (73 GPa), while decreases to 5.7 K at 80 GPa and almost disappears at 110 GPa, consisting with experimental phenomenon that there was no superconducting transition observed down to 4 K over a wide pressure range 110-164 GPa. It is found that the soft phonon mode for branch 1, namely, the lowest acoustic mode, plays a crucial role in elevating the total EPC parameter λ of cubic AlH3. And the evolution of Tc with pressure follows the corresponding change of this soft mode, i.e. this mode is responsible for the disappearance of Tc in experiments. Meanwhile, the softening of this lowest acoustic mode originates from the electronic momentum transfer from M to R point. This phenomenon provides an important insight into why drastic changes in the diffraction pattern were observed in the pressure range of 63-73 GPa in Goncharenko's experiments. Specifically, once finite electronic temperature effects are included, we find that dynamical instabilities can be removed in the phonon dispersion for P ≥63 GPa, rendering the metastability of this phase in the range of 63-73 GPa, and Tc (15.4 K) becomes remarkably high under the lowest possible pressure (63 GPa) compared with that of under 73 GPa (8.5 K). Our calculations open the possibility that finite temperature may allow cubic AlH3 to be dynamically stabilized even for pressures below 73 GPa. It is reasonable to deduced that if special techniques, such as rapid decompression, quenching, and annealing, are implemented in experiments, higher Tc can be observed in hydrides or hydrogen-rich compounds under much lower pressure than ever before.

  2. Once a physicist: Alan Pierson

    NASA Astrophysics Data System (ADS)

    2016-08-01

    Alan Pierson is artistic director and conductor of the New York-based contemporary-music ensemble Alarm Will Sound, and a professor of conducting at Northwestern University's Bienen School of Music in Illinois

  3. Automated calculation of fundamental frequencies: Application to AlH3 using the coupled-cluster singles-and-doubles with perturbative triples method

    NASA Astrophysics Data System (ADS)

    Ruden, T. A.; Taylor, P. R.; Helgaker, T.

    2003-07-01

    An automated scheme for calculating numerical derivatives of functions is presented and applied to the Taylor expansion of potential energy surfaces. The computational cost is reduced by invoking the symmetry properties of noncubic groups. The scheme is applied to the quartic force field of isotopomers of AlH3 by numerical differentiation of the CCSD(T) energy, using the cc-pCVQZ basis for the harmonic part of the potential and the cc-pCVTZ basis for the anharmonic part. From this force field, zero-order vibrational corrections to the geometry and the fundamental frequencies are calculated by second-order perturbation theory. The results are compared with experiment and previous calculations.

  4. SHEPARD, ALAN - ASTRONAUT - SUIT - CAPE

    NASA Image and Video Library

    1961-01-01

    S61-03651 (5 May 1961) --- Astronaut Alan B. Shepard Jr., in his pressure suit and helmet, is being inserted into the Freedom 7 capsule in preparation for the Mercury-Redstone 3 (MR-3) mission. Photo credit: NASA or National Aeronautics and Space Administration

  5. Reaction of dimethylethylamine alane and ammonia on Si(100) during the atomic layer growth of AlN: static SIMS, TPSIMS, and TPD

    NASA Astrophysics Data System (ADS)

    Kuo, J. S.; Rogers, J. W.

    2000-05-01

    Dimethylethylamine alane [DMEAA; AlH 3:N(CH 3) 2(CH 2CH 3)] has been used as an Al source in the chemical vapor deposition of AlN. In the atomic layer growth mode, ammonia and DMEAA interact selectively by nucleophilic displacement. In the first part of this study, the surface adsorption and reaction processes are characterized with static secondary-ion mass spectrometry and temperature-programmed secondary-ion mass spectrometry. The secondary ion emission from DMEAA-covered Si surface shares similar general characteristics with the gas phase cracking pattern. The secondary ion emission spectrum is interpreted according to a unimolecular ion decomposition mechanism and is used as the fingerprint for the presence of molecular DMEAA. During the surface reaction between DMEAA and ammonia, the intensity of the fingerprint peaks diminish, representing the departure of the amine ligand. The thermal stability of DMEAA and its decomposition behavior on Si are also examined.

  6. Atomic Simulations of Alane Phase Transformations and Dehydrogenation Mechanisms

    NASA Astrophysics Data System (ADS)

    Opalka, Susanne; Saxe, Paul; Lovvik, Ole Martin

    2007-03-01

    Density functional theory atomic ground state, molecular dynamics, and direct method lattice dynamic simulations were used to mechanistically probe phase transformations between the various crystallographically refined α, α', β, and γ AlH3 phases. Lattice dynamic predictions of the AlH3 structures provided an ideal test case for systematically accessing the accuracy of the vibrational thermodynamic property contributions with the harmonic approximation. The predicted transformation pathways involved coordinated tilting and rotation mechanisms, similar to that observed in perovskite structures. Further simulations were conducted to elucidate the mechanism for α AlH3 phase decomposition to the Al and H2 products and to identify probable barriers to reversible rehydrogenation.

  7. Density Functional Theory Based Kinetic Monte Carlo Approach for Understanding Atomistic Mechanisms for Reversible Hydrogen Storage in Metal Hydrides: Application to Alane Formation on Ti Doped Al Surfaces

    NASA Astrophysics Data System (ADS)

    Karim, A.; Muckerman, J.; Sutter, P.; Muller, E.

    2008-03-01

    We describe a density functional kinetic Monte Carlo approach enabling us to study and simulate the steady-state situation of dissociative adsorption of hydrogen along with diffusion and reaction of Al and H atoms leading towards the formation of alane species on Ti-doped Al surfaces. In the first step, density functional theory is used in conjunction with the nudged elastic band/drag method to obtain the energetics of the relevant atomistic processes of Al and H diffusion and their reactions on Al surfaces with different concentration of dopant Ti atoms. Subsequently, the kinetic Monte Carlo method is employed, which accounts for the spatial distribution, fluctuations, and evolution of chemical species at Ti-doped Al surfaces under steady-state conditions. This DFT-based KMC approach provides an insight into the kinetics of alanes at technologically relevant pressure and temperature conditions. Our computed production rates of AlH3 on Al surfaces are in agreement with experimental data. We also obtained temperature programmed desorption spectra of different alane species, which is agreeing well with experiments.

  8. Computational study of pristine and titanium-doped sodium alanates for hydrogen storage applications

    NASA Astrophysics Data System (ADS)

    Dathar, Gopi Krishna Phani

    The emphasis of this research is to study and elucidate the underlying mechanisms of reversible hydrogen storage in pristine and Ti-doped sodium aluminum hydrides using molecular modeling techniques. An early breakthrough in using complex metal hydrides as hydrogen storage materials is from the research on sodium alanates by Bogdanovic et al., in 1997 reporting reversible hydrogen storage is possible at moderate temperatures and pressures in transition metal doped sodium alanates. Anton reported titanium salts as the best catalysts compared to all other transition metal salts from his further research on transition metal doped sodium alanates. However, a few questions remained unanswered regarding the role of Ti in reversible hydrogen storage of sodium alanates with improved thermodynamics and kinetics of hydrogen desorption. The first question is about the position of transition metal dopants in the sodium aluminum hydride lattice. The position is investigated by identifying the possible sites for titanium dopants in NaAlH4 lattice and studying the structure and dynamics of possible compounds resulting from titanium doping in sodium alanates. The second question is the role of titanium dopants in improved thermodynamics of hydrogen desorption in Ti-doped NaAlH4. Though it is accepted in the literature that formation of TiAl alloys (Ti-Al and TiAl3) is favorable, reaction pathways are not clearly established. Furthermore, the source of aluminum for Ti-Al alloy formation is not clearly understood. The third question in this area is the role of titanium dopants in improved kinetics of hydrogen absorption and desorption in Ti-doped sodium alanates. This study is directed towards addressing the three longstanding questions in this area. Thermodynamic and kinetic pathways for hydrogen desorption in pristine NaAlH4 and formation of Ti-Al alloys in Ti-doped NaAlH 4, are elucidated to understand the underlying mechanisms of hydrogen desorption. Density functional theory

  9. Portrait of Astronaut Alan L. Bean

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Portrait of Astronaut Alan L. Bean, Prime Crew Lunar Module Pilot of the Apollo 12 Lunar Landing Mission, in his space suit minus the helmet. He is standing outside beside a mock-up of the Lunar Lander.

  10. Portrait of Astronaut Alan L. Bean

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Portrait of Astronaut Alan L. Bean, Prime Crew Lunar Module Pilot of the Apollo 12 Lunar Landing Mission, in his space suit minus the helmet. He is standing outside beside a mock-up of the Lunar Lander.

  11. ASTRONAUT ALAN SHEPARD - FREEDOM "7" - LIFTOFF - CAPE

    NASA Image and Video Library

    1961-05-05

    S61-02409 (5 May 1961) --- Launching of the Mercury-Redstone 3 (MR-3) rocket from Cape Canaveral on astronaut Alan B. Shepard?s suborbital mission. Photo credit: NASA or National Aeronautics and Space Administration

  12. ASTRONAUT ALAN SHEPARD - PREFLIGHT ACTIVITIES - CAPE

    NASA Image and Video Library

    1961-01-01

    S61-02767 (5 May 1961) --- Astronaut Alan B. Shepard Jr. in flight couch for final check before insertion into capsule for his Mercury-Redstone 3 (MR-3) flight. Photo credit: NASA or National Aeronautics and Space Administration

  13. SHEPARD, ALAN B., ASTRONAUT - MISC. - PA

    NASA Image and Video Library

    1960-01-01

    G60-02402 (1960) --- Astronaut Alan B. Shepard Jr. prepares for testing in a capsule of the U.S. Navy's centrifuge at Johnsville, Pennsylvania. Photo credit: NASA or National Aeronautics and Space Administration

  14. Astronaut Alan Bean shaves while aboard Skylab

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, uses battery powered shaver while in the crew quarters of the Skylab space station's Orbital Workshop (OWS) crew quarters. This photograph was taken with a 35mm Nikon camera held by one of Bean's fellow crewmen during the 56.5 day second manned Skylab mission in Earth orbit.

  15. Alan Bullock: Historian, Social Democrat and Chairman

    ERIC Educational Resources Information Center

    Caston, Geoffrey

    2006-01-01

    This study considers the influence on British education (particularly schools) of Alan Bullock, Vice-Chancellor of Oxford University from 1969 to 1973 and distinguished contemporary historian. It quotes extensively from Bullock's own writings, including his developing personal views on education, and reflections on his own experiences. Following a…

  16. SHEPARD, ALAN B., JR. ASTRONAUT - WASHINGTON, DC

    NASA Image and Video Library

    1963-05-06

    S63-06268 (8 May 1963) --- Astronaut Alan B. Shepard, Jr., receives his NASA's Distinguished Service Medal from President John F. Kennedy, after his Mercury-Redstone 3 (MR-3) flight, in a Rose Garden ceremony on May 8, 1961 at the White House.

  17. Automotive storage of hydrogen in alane.

    SciTech Connect

    Ahluwalia, R. K.; Hua, T. Q.; Peng, J.-K.; Nuclear Engineering Division

    2009-09-01

    Although alane (AlH{sub 3}) has many interesting properties as a hydrogen storage material, it cannot be regenerated on-board a vehicle. One way of overcoming this limitation is to formulate an alane slurry that can be easily loaded into a fuel tank and removed for off-board regeneration. In this paper, we analyze the performance of an on-board hydrogen storage system that uses alane slurry as the hydrogen carrier. A model for the on-board storage system was developed to analyze the AlH{sub 3} decomposition kinetics, heat transfer requirements, stability, startup energy and time, H{sub 2} buffer requirements, storage efficiency, and hydrogen storage capacities. The results from the model indicate that reactor temperatures higher than 200 C are needed to decompose alane at reasonable liquid hourly space velocities, i.e., > 60 h{sup -1}. At the system level, a gravimetric capacity of 4.2 wt% usable hydrogen and a volumetric capacity of 50 g H{sub 2}/L may be achievable with a 70% solids slurry. Under optimum conditions, {approx}80% of the H{sub 2} stored in the slurry may be available for the fuel cell engine. The model indicates that H{sub 2} loss is limited by the decomposition kinetics rather than by the rate of heat transfer from the ambient to the slurry tank.

  18. Rear View - Astronaut Alan Shepard - Pressure Suit

    NASA Image and Video Library

    1961-01-01

    S61-02796 (5 May 1961) --- Rear view of astronaut Alan B. Shepard Jr., in his pressure suit and helmet, as he approaches the Freedom 7 capsule in preparation for ingress before the Mercury-Redstone 3 mission. All that can be seen of the astronaut is his legs. Photo credit: NASA or National Aeronautics and Space Administration

  19. Low-Energy Polymeric Phases of Alanates

    NASA Astrophysics Data System (ADS)

    Huan, Tran Doan; Amsler, Maximilian; Marques, Miguel A. L.; Botti, Silvana; Willand, Alexander; Goedecker, Stefan

    2013-03-01

    Low-energy structures of alanates are currently known to be described by patterns of isolated, nearly ideal tetrahedral [AlH4] anions and metal cations. We discover that the novel polymeric motif recently proposed for LiAlH4 plays a dominant role in a series of alanates, including LiAlH4, NaAlH4, KAlH4, Mg(AlH4)2, Ca(AlH4)2, and Sr(AlH4)2. In particular, most of the low-energy structures discovered for the whole series are characterized by networks of corner-sharing [AlH6] octahedra, forming wires and/or planes throughout the materials. Finally, for Mg(AlH4)2 and Sr(AlH4)2, we identify two polymeric phases to be lowest in energy at low temperatures.

  20. Understanding and Quantifying the Reactivity of Energetic NanoParticles and NanoComposites

    DTIC Science & Technology

    2015-01-05

    Aerosol Synthesis and Reactivity of Thin Oxide Shell Aluminum Nanoparticles via Fluorocarboxylic Acid Functional Coating, Particle & Particle...Received Paper G. Feng,, S. Chowdhury, G. Jian,, M.R Zachariah. Modified Aerosol Routes to Core-Shell Nano-Energetic Materials Synthesis , Materials...Hydride (- AlH3 ) was also conducted. In this study the ignition characteristics were determined through the use of two separate modified T-jump

  1. A therapist's response to Alan Waterman.

    PubMed

    Serlin, Ilene A

    2014-01-01

    Comments on the article "The humanistic psychology-positive psychology divide: Contrasts in philosophical foundations" by Waterman (see record 2013-12501-001). Alan Waterman's article brought a useful discerning eye to the differences between humanistic and positive psychology and their different theoretical and methodological assumptions. It is important that these differences not be glossed over too quickly by those who seek complementarity or integration of the two. However, Waterman also polarized them unnecessarily, which is unfortunate. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  2. Astronaut Alan L. Bean - Family - Houston, TX

    NASA Image and Video Library

    1973-07-05

    S73-31104 (17 July 1973) --- The wife and children of astronaut Alan L. Bean are photographed at their home near the Johnson Space Center (JSC), where their husband and father is preparing for NASA?s second manned Skylab mission. Bean is commander of the Skylab 3 Earth-orbital mission and will be joined by scientist-astronaut Owen K. Garriott, science pilot, and astronaut Jack R. Lousma, pilot for the schedule two-month mission. With Mrs. Sue Bean are the couple?s children Clay, 17, and Amy Sue, 10; and the family?s pet dog. Photo credit: NASA

  3. Obituary: Alan D. Fiala (1942-2010)

    NASA Astrophysics Data System (ADS)

    Kaplan, George

    2011-12-01

    Dr. Alan Dale Fiala, astronomer and expert on solar eclipses, died on May 26, 2010 in Arlington, Virginia, of respiratory failure after a brief illness. He was 67. Fiala had been a staff astronomer at the U.S. Naval Observatory in Washington, D.C., for his entire professional career, where he rose from a position as a summer intern to become the Chief of the Nautical Almanac Office, responsible for annual publications for astronomy and navigation that are used the world over. He retired from the observatory in 2000. Although a childhood case of polio affected his mobility for the rest of his life, he seldom let his physical constraints limit his activities, which were many and varied. Alan Fiala was born in Beatrice, Nebraska on November 9, 1942, the middle son of Emil A. ("John") and Lora Marie Fiala. Fiala's father was a postal clerk and Civil Service examiner. Fiala expressed interest in astronomy at a very young age. He contracted polio when he was 9. He graduated from Beatrice High School in 1960 with a straight-A average and went on to study at Carleton College. He received his B.A. summa cum laude after three years, in 1963, with a major in astronomy and minors in physics and mathematics. He was elected to Phi Beta Kappa, Sigma Xi, and Pi Mu Epsilon (mathematics). In 1962, Alan Fiala obtained a job as a summer intern at the Naval Observatory in Washington, working in the Nautical Almanac Office (NAO). He entered the graduate program at Yale University and continued to work summers at the observatory. He received his Ph.D. in 1968, under Gerald Clemence. His dissertation was titled "Determination of the Mass of Jupiter from a Study of the Motion of 57 Mnemosyne." After receiving his doctorate, Fiala became a permanent member of the Naval Observatory staff. Computers were just being introduced there and he participated in the automation of many procedures used to prepare the annual publications of the Nautical Almanac Office. One of his first assignments was

  4. Low-Energy Polymeric Phases of Alanates

    NASA Astrophysics Data System (ADS)

    Tran, Huan; Amsler, Maximilian; Marques, Miguel; Botti, Silvana; Willand, Alexander; Goedecker, Stefan

    2013-03-01

    Low-energy structures of alanates are currently known to be described by patterns of isolated, nearly ideal tetrahedral [AlH4] anions and metal cations. We discover that the novel polymeric motif recently proposed for LiAlH4 plays a dominant role in a series of alanates, including LiAlH4, NaAlH4, KAlH4, Mg(AlH4)2, Ca(AlH4)2 and Sr(AlH4)2. In particular, most of the low-energy structures discovered for the whole series are characterized by networks of corner-sharing [AlH6] octahedra, forming wires and/or planes throughout the materials. Finally, for Mg(AlH4)2 and Sr(AlH4)2, we identify two polymeric phases to be lowest in energy at low temperatures. Work supported by Swiss NSF. Computational resources were provided by the Swiss National Supercomputing Center (CSCS) in Lugano.

  5. A parallel vectorized implementation of triple excitations in CCSD(T) - Application to the binding energies of the AlH3, AlH2F, AlHF2 and AlF3 dimers

    NASA Technical Reports Server (NTRS)

    Rendell, Alistair P.; Lee, Timothy J.; Komornicki, Andrew

    1991-01-01

    An efficient method for various noniterative estimates of connected triple excitations in coupled-cluster theory is outlined and related to a similar expression occurring in Moller-Plesset perturbation theory. The method is highly vectorized and capable of utilizing multiple processors on a shared-memory machine, leading to computational rates in excess of one billion floating-point operations per second on four processors of a CRAY Y-MP. Using the new procedure, the binding energies of the D(2h) diborane-type dimers of AlH3, AlH2F, AlHF2, and AlF3 have been determined to be 32, 40, 20, and 47 kcal/mol, respectively. For Al2F6, the correlation procedure includes 232 molecular orbitals and over 1.5 x 10 to the 6th single and double coupled-cluster amplitudes, effectively accounting for over 2 x 10 to the 9th connected triple excitations.

  6. A phenomenologist's response to Alan Waterman.

    PubMed

    Morley, James

    2014-01-01

    Comments on the article "The humanistic psychology-positive psychology divide: Contrasts in philosophical foundations" by Waterman (see record 2013-12501-001). Distancing positive psychology from humanistic psychology, Alan Waterman wishes to close the conversation between the two cognate psychological paradigms. It's true that strong fences can make good neighbors, and a desire for amicable separation on the basis of irreconcilable differences is understandable. The current author believes that Waterman's gracious style is an exemplary model for respectful disagreement. However, in distancing positive psychology from humanistic psychology generally, Waterman represented phenomenology as the philosophical foundation to humanistic psychology in a way that is seriously mistaken at worst and problematic at best. Putting aside the issue of the relationship between phenomenology and humanistic psychology (as well as positive psychology), this brief commentary will limit itself to those points where Waterman invoked the term phenomenological with broad strokes that invite friendly clarification. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  7. Remembering James Alan Bassham (1922-2012).

    PubMed

    Govindjee; Bassham, Helen; Bassham, Susan

    2016-04-01

    James Alan Bassham, known to many as Al, was born on November 26, 1922, in Sacramento, California (CA), USA. He died on November 19, 2012, in El Cerrito, CA. To celebrate his life at his 3rd death anniversary, we present here a brief biography, comments on his discoveries, but most importantly, remembrances from family and friends; we remember this wonderful and modest person who had played a major pivotal role in the discoveries that led to what he would like to call the P(hotosynthetic) C(arbon) R(eduction) cycle, known to many as the Calvin Cycle, the Calvin-Benson Cycle, or the Calvin-Benson-Bassham Cycle. Based on a personal request by Bassham himself to one of us (Govindjee), we refrain from including his name in the cycle-in recognition of his many students and associates he would have liked to honor.

  8. Astronaut Alan Shepard receives MASA Distinguished Service award

    NASA Technical Reports Server (NTRS)

    1988-01-01

    Astronaut Alan B. Shepard recieves the NASA Distinguished Service Award from President John F. Kennedy in May 1961, days after his history making MR-3 flight (31387); Alan Shepard and his wife wave to the crowd after Shepard received the NASA Distinguished Service Award from President John F. Kennedy (31388).

  9. Methods for synthesizing alane without the formation of adducts and free of halides

    DOEpatents

    Zidan, Ragaiy; Knight, Douglas A; Dinh, Long V

    2013-02-19

    A process is provided to synthesize an alane without the formation of alane adducts as a precursor. The resulting product is a crystallized .alpha.-alane and is a highly stable product and is free of halides.

  10. Sodium alanate nanoparticles--linking size to hydrogen storage properties.

    PubMed

    Baldé, Cornelis P; Hereijgers, Bart P C; Bitter, Johannes H; de Jong, Krijn P

    2008-05-28

    Important limitations in the application of light metal hydrides for hydrogen storage are slow kinetics and poor reversibility. To alleviate these problems doping and ball-milling are commonly applied, for NaAlH 4 leading to particle sizes down to 150 nm. By wet-chemical synthesis we have prepared carbon nanofiber-supported NaAlH 4 with discrete particle size ranges of 1-10 microm, 19-30 nm, and 2-10 nm. The hydrogen desorption temperatures and activation energies decreased from 186 degrees C and 116 kJ.mol (-1) for the largest particles to 70 degrees C and 58 kJ.mol (-1) for the smallest particles. In addition, decreasing particle sizes lowered the pressures needed for reloading. This reported size-performance correlation for NaAlH 4 may guide hydrogen storage research for a wide range of nanostructured light (metal) hydrides.

  11. Astronaut Alan Bean works on Modular Equipment Stowage Assembly

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, works at the Modular Equipment Stowage Assembly (MESA) on the Apollo 12 Lunar Module during the mission's first extravehicular activity, EVA-1, on November 19, 1969.

  12. Astronaut Alan Bean participates in lunar surface simulation

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot of the Apollo 12 lunar landing mission, participates in lunar surface simulation training in bldg 29 at the Manned Spacecraft Center. Bean is strapped to a one-sixth gravity simulator.

  13. The making of an advocate. Interview with Alan Fernandez.

    PubMed

    Fernandez, Alan

    2012-11-01

    We spoke with Alan, Associate Director at the Genetics Policy Institute (GPI), the organizer of the annual World Stem Cell Summit, to find out what led him to devote his career to stem cell advocacy. Alan has focused his career on advancing stem cell sciences and the field of regenerative medicine since 2006. While working with Burrill & Company, he began working with the Genetics Policy Institute (GPI) on the 2007 Stem Cell Summit with the Harvard Stem Cell Institute. He then joined the GPI full-time in 2008. Alan's skills in business development and marketing were cultivated at companies like Dow Jones, Ziff Davis and Burrill & Company. Earlier in his career, Alan worked in technology and grassroots business communications, working for start-ups and mid-sized companies.

  14. Astronaut Alan Bean participates in lunar surface simulation

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot of the Apollo 12 lunar landing mission, participates in lunar surface simulation training in bldg 29 at the Manned Spacecraft Center. Bean is strapped to a one-sixth gravity simulator.

  15. Alan Shepard Hits A Golf Ball on the Moon

    NASA Image and Video Library

    Apollo 14 Commander and original Mercury astronaut Alan Shepard, the first American to fly in space, tees off on the lunar surface during his 1971 mission, with crewmate Edgar Mitchell watching and...

  16. Surface investigations of the atomic layer growth mechanism in aluminum nitride thin film deposition using dimethylethylamine alane and ammonia

    NASA Astrophysics Data System (ADS)

    Kuo, Jason Se-Yung

    Aluminum Nitride (AlN), a wide-bandgap semiconductor, has been shown to be an extremely versatile material in semiconductor applications. Our previous efforts in formulating a Metalorganic Chemical Vapor Deposition (MOCVD) processing strategy to deposit AN using Dimethylethylamine Alane (DMEAA; AlH3:N(CH3)2CH2CH3) and ammonia resulted in high quality film growth at low temperatures (˜600 K). Understanding the surface reactions involved is a key step in successfully optimizing a MOCVD process. In this research, we investigated the surface interactions between DMEAA and ammonia leading to the Atomic Layer Growth (ALG) mode on a Si(100) surface using a combination of surface analysis techniques, including Secondary-Ion Mass Spectrometry (SIMS), Temperature-Programmed SIMS (TPSIMS), X-ray Photoelectron Spectroscopy (XPS), and Temperature-Programmed Desorption (TPD). The exposure of Si(100) to DMEAA at 310 K resulted in self-limiting adsorption of molecular DMEAA and Dimethylethylamine (DMEA). Based on the stoichiometric information from XPS, the molecularly adsorbed DMEA most likely originated from the exposure of a mixed DMEAA-DMEA gas phase rather than a dissociative adsorption process. The DMEAA molecule is susceptible to thermal decomposition, as the aminealane adduct configuration was no longer observed above 490 K. This can impose an upper temperature limit in developing a processing strategy. The chemical interaction between ammonia and DMEAA resulted in a displacement of DMEA by ammonia. A new surface intermediate (AlHND2) was detected with both SIMS and XPS. This displacement mechanism was rationalized using Hard-Soft-Acid-Base (HSAB) theory. We were able to observe, in a step-by-step fashion, the atomic layer growth process by monitoring the C:N ratios using XPS. The resulting AlN film contained substantial hydrogen but the hydrogen content may be removed thermally. Atomic layer growth mechanism provides an effective means to grow high quality thin films by

  17. Alan Shepard in the Rendezvous Docking Simulator

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut Alan Shepard (right) was one of 14 astronauts, 8 NASA test pilots, and 2 McDonnell test pilots who took part in simulator studies. Shepard flew the simulator on November 14, 1963. A.W. Vogeley wrote: 'Many of the astronauts have flown this simulator in support of the Gemini studies and they, without exception, appreciated the realism of the visual scene. The simulator has also been used in the development of pilot techniques to handle certain jet malfunctions in order that aborts could be avoided. In these situations large attitude changes are sometimes necessary and the false motion cues that were generated due to earth gravity were somewhat objectionable; however, the pilots were readily able to overlook these false motion cues in favor of the visual realism.' Roy F. Brissenden noted that: 'The basic Gemini control studies developed the necessary techniques and demonstrated the ability of human pilots to perform final space docking with the specified Gemini-Agena systems using only visual references. ... Results... showed that trained astronauts can effect the docking with direct acceleration control and even with jet malfunctions as long as good visual conditions exist.... Probably more important than data results was the early confidence that the astronauts themselves gained in their ability to perform the maneuver in the ultimate flight mission.' Shepard commented: 'I had the feeling tonight - a couple of times - that I was actually doing the space mission instead of the simulation. As I said before, I think it is a very good simulation.' Shepard also commented on piloting techniques. Most astronauts arrived at this same preferred technique: Shepard: 'I believe I have developed the preferred technique for these conditions and the technique appeared to me to be best was to come in slightly above the target so that I was able to use the longitudinal marks on the body of the target as a reference, particularly for a lateral translation and, of course, I

  18. Formation and properties of stabilized aluminum nanoparticles.

    PubMed

    Meziani, Mohammed J; Bunker, Christopher E; Lu, Fushen; Li, Heting; Wang, Wei; Guliants, Elena A; Quinn, Robert A; Sun, Ya-Ping

    2009-03-01

    The wet-chemical synthesis of aluminum nanoparticles was investigated systematically by using dimethylethylamine alane and 1-methylpyrrolidine alane as precursors and molecules with one or a pair of carboxylic acid groups as surface passivation agents. Dimethylethylamine alane was more reactive, capable of yielding well-defined and dispersed aluminum nanoparticles. 1-Methylpyrrolidine alane was less reactive and more complex in the catalytic decomposition reaction, for which various experimental parameters and conditions were used and evaluated. The results suggested that the passivation agent played dual roles of trapping aluminum particles to keep them nanoscale during the alane decomposition and protecting the aluminum nanoparticles postproduction from surface oxidation and that an appropriate balance between the rate of alane decomposition (depending more sensitively on the reaction temperature) and the timing in the introduction of the passivation agent into the reaction mixture was critical to the desired product mixes and/or morphologies. Some fundamental and technical issues on the alane decomposition and the protection of the resulting aluminum nanoparticles are discussed.

  19. σ-Alane complexes of chromium, tungsten, and manganese.

    PubMed

    Riddlestone, Ian M; Edmonds, Siân; Kaufman, Paul A; Urbano, Juan; Bates, Joshua I; Kelly, Michael J; Thompson, Amber L; Taylor, Russell; Aldridge, Simon

    2012-02-08

    Photolytic ligand displacement and salt metathesis routes have been exploited to give access to κ(1) σ-alane complexes featuring Al-H bonds bound to [W(CO)(5)] and [Cp'Mn(CO)(2)] fragments, together with a related κ(2) complex of [Cr(CO)(4)]. Spectroscopic, crystallographic, and quantum chemical studies are consistent with the alane ligands acting predominantly as σ-donors, with the resulting binding energies calculated to be marginally greater than those found for related dihydrogen complexes.

  20. 40 Years in Applied Linguistics: An Interview with Alan Davies

    ERIC Educational Resources Information Center

    Kunnan, Antony John

    2005-01-01

    This article presents an interview with Professor Alan Davies who was born in Wales, studied at Oxford University and Birmingham University, and taught in Scotland at the University of Edinburgh, completing 40 years this year. Professor Davies has travelled widely to give invited talks and seminars, participate in applied linguistics conferences,…

  1. Astronaut Alan Bean with subpackages of the ALSEP during EVA

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, traverses with the two subpackages of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA). Bean deployed the ALSEP components 300 feet from the Lunar Module (LM). The LM and deployed erectable S-band antenna can be seen in the background.

  2. Astronaut Alan Bean doing acrobatics in OWS dome area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, doing acrobatics in the dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. The dome area is about 22 feet in diameter and 19 feet from top to bottom.

  3. Astronaut Alan Bean holds Special Environmental Sample Container

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, holds a Special Environmental Sample Container filled with lunar soil collected during the extravehicular activity (EVA) in which Astronauts Charles Conrad Jr., commander, and Bean participated. Connrad, who took this picture, is reflected in the helmet visor of the lunar module pilot.

  4. Astronaut Alan Bean deploys Lunar Surface Magnetometer on lunar surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, deploys the Lunar Surface Magnetometer (LSM) during the first Apollo 12 extravehicular activity on the Moon. The LSM is a component of the Apollo Lunar Surface Experiments Package (ALSEP). The Lunar Module can be seen in the left background.

  5. Astronaut Owen Garriott trims hair of Astronaut Alan Bean

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, trims the hair of Astronaut Alan L. Bean, commander, in this on-board photograph from the Skylab Orbital Workshop (OWS). Bean holds a vacuum hose to gather in loose hair.

  6. Understanding the Scientific Enterprise: A Conversation with Alan Leshner

    ERIC Educational Resources Information Center

    Perkins-Gough, Deborah

    2007-01-01

    Understanding the nature of science is even more important than mastering its details, says Alan Leshner, Chief Executive Officer of the American Association for the Advancement of Science, in an interview with Educational Leadership. In this article, Leshner discusses the controversy about teaching evolution, and he asserts that demands to…

  7. Astronaut Alan Bean doing acrobatics in OWS dome area

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, doing acrobatics in the dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. The dome area is about 22 feet in diameter and 19 feet from top to bottom.

  8. Astronaut Alan Bean holds Special Environmental Sample Container

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, holds a Special Environmental Sample Container filled with lunar soil collected during the extravehicular activity (EVA) in which Astronauts Charles Conrad Jr., commander, and Bean participated. Connrad, who took this picture, is reflected in the helmet visor of the lunar module pilot.

  9. Astronaut Owen Garriott trims hair of Astronaut Alan Bean

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Scientist-Astronaut Owen K. Garriott, Skylab 3 science pilot, trims the hair of Astronaut Alan L. Bean, commander, in this on-board photograph from the Skylab Orbital Workshop (OWS). Bean holds a vacuum hose to gather in loose hair.

  10. Critique as Homiletics: A Response to Alan Block

    ERIC Educational Resources Information Center

    Mayes, Clifford; Mayes, Pamela Blackwell; Williams, Ellen

    2004-01-01

    Alan Block's (2004) major criticism of the authors' study revolves around the notion that they have attempted to quantify their students' sense of calling in an existentially inauthentic, spiritually delimiting way. For, as he puts it, "identifications of presence are impossible." The authors cannot accept this pronouncement if only for the simple…

  11. Understanding the Scientific Enterprise: A Conversation with Alan Leshner

    ERIC Educational Resources Information Center

    Perkins-Gough, Deborah

    2007-01-01

    Understanding the nature of science is even more important than mastering its details, says Alan Leshner, Chief Executive Officer of the American Association for the Advancement of Science, in an interview with Educational Leadership. In this article, Leshner discusses the controversy about teaching evolution, and he asserts that demands to…

  12. Astronaut Alan Bean with subpackages of the ALSEP during EVA

    NASA Image and Video Library

    1969-11-19

    AS12-46-6807 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot, traverses with the two sub packages of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA). Bean deployed the ALSEP components 300 feet from the Lunar Module (LM). The LM and deployed erectable S-band antenna can be seen in the background.

  13. Astronaut Alan Shepard recieves NASA Distinguished Service Award

    NASA Image and Video Library

    1961-05-07

    S67-19572 (8 May 1961) --- Astronaut Alan B. Shepard Jr. receives the NASA Distinguished Service Award from United States President John F. Kennedy May 8, 1961, days after his history making MR-3 flight. Shepard's wife and mother on left and the other six Mercury astronauts are in background. Photo credit: NASA or National Aeronautics and Space Administration

  14. Astronaut Alan Bean deploys Lunar Surface Magnetometer on lunar surface

    NASA Image and Video Library

    1969-11-19

    Astronaut Alan L. Bean, lunar module pilot, deploys the Lunar Surface Magnetometer (LSM) during the first Apollo 12 extravehicular activity on the Moon. The LSM is a component of the Apollo Lunar Surface Experiments Package (ALSEP). The Lunar Module can be seen in the left background.

  15. Astronaut Alan Bean participates in lunar surface simulation

    NASA Image and Video Library

    1969-10-29

    S69-56059 (24 Oct. 1969) --- Astronaut Alan L. Bean, lunar module pilot of the Apollo 12 lunar landing mission, participates in lunar surface simulation training in Building 29 at the Manned Spacecraft Center (MSC). Bean is strapped to a one-sixth gravity simulator.

  16. Astronaut Alan Shepard in pressure suit with Freedom 7 capsule

    NASA Image and Video Library

    1961-01-01

    S61-02547 (5 May 1961) --- Astronaut Alan B. Shepard Jr., in his pressure suit and helmet, looks into the Freedom 7 capsule in preparation for ingress before the Mercury-Redstone 3 (MR-3) mission. Photo credit: NASA or National Aeronautics and Space Administration

  17. CLOSEUP - ASTRONAUT SHEPARD, ALAN - PRESSURE SUIT - FREEDOM 7 CAPSULE

    NASA Image and Video Library

    1961-07-01

    S61-03645 (5 May 1961) --- Close-up of astronaut Alan B. Shepard Jr., in his pressure suit and helmet, ingressing into the Freedom 7 capsule in preparation for the Mercury-Redstone 3 (MR-3) mission. Photo credit: NASA or National Aeronautics and Space Administration

  18. 40 Years in Applied Linguistics: An Interview with Alan Davies

    ERIC Educational Resources Information Center

    Kunnan, Antony John

    2005-01-01

    This article presents an interview with Professor Alan Davies who was born in Wales, studied at Oxford University and Birmingham University, and taught in Scotland at the University of Edinburgh, completing 40 years this year. Professor Davies has travelled widely to give invited talks and seminars, participate in applied linguistics conferences,…

  19. Elucidation of hydrogen-release mechanism from methylamine in the presence of borane, alane, diborane, dialane, and borane-alane

    NASA Astrophysics Data System (ADS)

    Wang, Li; Zhang, Ting; He, Hongqing; Zhang, Jinglai

    2015-01-01

    The mechanisms of hydrogen release from methylamine with or without borane, alane, diborane, dialane, and borane-alane are theoretically explored. Geometries of stationary points are optimised at the MP2/aug-cc-pVDZ level and energy profiles are refined at the CCSD(T)/aug-cc-pVTZ level based on the second-order Møller-Plesset (MP2) optimised geometries. H2 elimination is impossible from the unimolecular CH3NH2 because of a high energy barrier. The results show that all catalysts can facilitate H2 loss from CH3NH2. However, borane or alane has no real catalytic effect because the H2 release is not preferred as compared with the B-N or Al-N bond cleavage once a corresponding adduct is formed. The diborane, dialane, and borane-alane will lead to a substantial reduction of energy barrier as a bifunctional catalyst. The similar and distinct points among various catalysts are compared. Hydrogen bond and six-membered ring formation are two crucial factors to decrease the energy barriers.

  20. 77 FR 74518 - Alan T. Waterman Award Committee; Notice of Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-14

    ... Alan T. Waterman Award Committee; Notice of Meeting In accordance with the Federal Advisory Committee...: Name: Alan T. Waterman Award Committee, 1172. Date and Time: January 11, 2013, 8:30a.m.-1:30 p.m. Place... Alan T. Waterman Award recipient. Agenda: To review and evaluate nominations as part of the...

  1. Alan E. Kazdin: Award for Distinguished Scientific Applications of Psychology.

    PubMed

    2011-11-01

    Presents Alan E. Kazdin, the 2011 winner of the American Psychological Association Award for Distinguished Scientific Applications of Psychology. "For outstanding and pathbreaking contributions to the understanding of the development, assessment, and treatment of psychopathology. Alan E. Kazdin's theoretically innovative, methodologically rigorous, and scientifically informed research has significantly advanced knowledge of child and adolescent psychopathologies such as depression and conduct problems. His writings on research strategies and methods have set a high standard for rigor in the field. His work and his ideas have had an enormous impact on the science, practice, and teaching of psychology, and his research has strengthened assessment and treatment of children and adolescents in scientific and clinical settings. His passion, energy, wisdom, and wit have inspired countless colleagues and students over the years, and his work will no doubt continue to do so for many generations to come." (PsycINFO Database Record (c) 2011 APA, all rights reserved).

  2. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the foreward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). This ASMU exerperiment is being done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  3. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the forward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). This ASMU exerperiment is being done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  4. Astronaut Alan Bean assisted with egressing command module after landing

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot, is assisted with egressing the Apollo 12 Command Module by a U.S. Navy underwater demolition team swimmer during recovery operations in the Pacific Ocean. Already in the life raft are Astronauts Charles Conrad Jr., commander; and Richard F. Gordon Jr., command module pilot. The Apollo 12 splashdown occured at 2:58 p.m., November 24, 1969 near American Samoa.

  5. Editors' overview for the Alan Turner Memorial volume

    NASA Astrophysics Data System (ADS)

    O'Regan, Hannah J.; Elton, Sarah; Schreve, Danielle

    2014-07-01

    The papers presented here, in this special volume dedicated to the memory of Alan Turner (1947-2012), provide a glimpse of the multi-faceted ways in which the mammalian fossil record can be investigated. The authors of contributions in this Special Issue are by no means an exhaustive list of his international collaborators and colleagues, and indeed, many are not represented here, but the contents cover many of the topics and issues that were of central archaeological and wider Quaternary mammalian interest to Alan. Although the papers are not intended to provide a comprehensive overview of all techniques that can be applied, the set nevertheless reveals a snapshot of the state-of-the-art and of some of the methods that have the potential to bring much more of the past to life. Alan always sought to move beyond the 'stamp-collecting' approach of simply listing which taxa were present at a site, attempting to elucidate what the presence of those animals might mean in terms of palaeoecology. In particular, the span of Alan's career has seen major advances in our understanding of Quaternary mammalian biostratigraphy and palaeobiogeography, the widespread application of novel techniques such as ancient DNA, the development of high-precision geochronology and the discovery of new hominin species. The papers presented here reflect those developments and highlight interdisciplinary approaches, from examination of sediments to careful measurements of the fossils themselves, from modelling the presence of taxa at particular points in the Quaternary to examination of the similarities and differences in fauna within and between sites.

  6. Astronaut Alan Shepard receives MASA Distinguished Service award

    NASA Image and Video Library

    1961-05-07

    S88-31387 (8 May 1961) --- President John F. Kennedy (left) congratulates NASA's Distinguished Service Medal Award recipient astronaut Alan B. Shepard Jr. in a Rose Garden ceremony on May 8, 1961, at the White House. Vice-President Lyndon B. Johnson, NASA Administrator James E. Webb and several NASA astronauts are in the background. Three days earlier, Shepard made history with a 15-minute suborbital space mission in the Freedom 7, Mercury-Redstone 3 spacecraft. Photo credit: NASA

  7. Astronaut Alan Shepard undergoes suiting up operations during Apollo 14

    NASA Image and Video Library

    1971-01-31

    S71-16638 (31 Jan. 1971) --- Astronaut Alan B. Shepard Jr., commander, undergoes suiting up operations at the Kennedy Space Center (KSC) during the Apollo 14 prelaunch countdown. Apollo 14, with astronauts Shepard; Edgar D. Mitchell, lunar module pilot; and Stuart A. Roosa, command module pilot; aboard was launched from Pad A, Launch Complex 39 at 4:03:02 p.m. (EST), Jan. 31, 1971.

  8. Astronaut Alan Shepard receives MASA Distinguished Service award

    NASA Image and Video Library

    1961-05-07

    S88-31388 (8 May 1961) --- Astronaut Alan B. Shepard Jr. (center), along with wife Louise, waves to a crowd outside the U.S. Capitol building. Shepard, Mercury-Redstone 3 astronaut, had earlier briefed Congress on the first U.S. manned spaceflight -- a 15-minute suborbital mission on May 5, 1961, aboard the Freedom 7 capsule. (NASA Hq. Photo No., MR3-49) Photo credit: NASA or National Aeronautics and Space Administration

  9. ASTRONAUT ALAN B. SHEPARD, JR. - PERSONAL (GT-11) - CAPE

    NASA Image and Video Library

    1966-09-12

    S66-50713 (12 Sept. 1966) --- Astronaut Alan B. Shepard Jr., Chief, MSC Astronaut Office, shields his eyes from the sun as he follows the Gemini-11 liftoff. Onboard were astronauts Charles Conrad Jr., command pilot, and Richard F. Gordon Jr., pilot, scheduled for a three-day mission in space. Liftoff was at 9:42 a.m. (EST), Sept. 12, 1966. Photo credit: NASA

  10. Astronaut Alan Shepard onboard helicopter after recovery of Mercury capsule

    NASA Image and Video Library

    1961-05-05

    S88-31383 (5 May 1961) --- Astronaut Alan B. Shepard Jr., Mercury-Redstone 3 (MR-3) pilot, jokes with doctors while in-flight between the U.S. Navy Carrier Champlain and the Grand Bahama Islands. Shepard is the first American in space with the successful completion of the 15-minute suborbital mission. Photo credit: NASA or National Aeronautics and Space Administration

  11. Crew Members - USS Champlain - Arrival - Astronaut Alan Shepard

    NASA Image and Video Library

    1961-01-01

    S61-02711 (5 May 1961) --- Crew members of the U.S. Navy Carrier Champlain cheer and take pictures of the arrival of the first Project Mercury pilot to fly a suborbital flight, astronaut Alan B. Shepard Jr. Two helicopters are approaching the ship, one carrying the astronaut and the other the Mercury-Redstone 3 (MR-3) capsule. Photo credit: NASA or National Aeronautics and Space Administration

  12. Kinetics of Thermal Decomposition of Aluminum Hydride in Argon

    DTIC Science & Technology

    2005-05-01

    investigate the decomposition kinetics of alane ( AlH3 ) in argon atmosphere and to shed light on the mechanism of alane decomposition. Two kinetic models...fastest is due to growth of the crystals. Thus, during decomposition, hydrogen gas is liberated and the initial polyhedra AlH3 crystals yield final...INTRODUCTION Recently, the interest in alane ( AlH3 ) as a solid rocket fuel has been renewed presumably after the development of new methods of

  13. Monomeric Alanes: Synthesis, Structure, and Thermolysis of MesAl(H)N(SiMe(3))(2) and a One-Pot Synthetic Route to Mes(2)AlH (Mes = -C(6)H(2)-2,4,6-t-Bu(3)).

    PubMed

    Wehmschulte, Rudolf J.; Power, Philip P.

    1998-05-04

    The reaction of (MesAlH(2))(2) (Mes = -C(6)H(2)-2,4,6-t-Bu(3)) with HN(SiMe(3))(2) affords the monomeric amidoarylalane MesAl(H)N(SiMe(3))(2), 1. This product can also be synthesized by the reaction of [MesAlH(2)](2) with LiN(SiMe(3))(2), which, in addition, yields the byproducts LiAlH(2){N(SiMe(3))(2)}(2), 3, and MesH. Thermolysis of 1 at 175-180 degrees C affords three different the related and the imide [MesAlN(SiMe(3))](n)(), 5. In addition, the previously reported monomeric alane Mes(2)AlH was synthesized in ca. 70% yield by a one-pot reaction between LiMes (generated in situ) and AlH(3).NMe(3). All products were spectroscopically characterized, and the structure of 1 was determined by X-ray crystallography. The Al-N distance (1.819(2) Å) in 1 is relatively long. However, it has a substantial, 18.5 kcal mol(-)(1), Al-N rotation barrier which is attributed to steric congestion rather than Al-N pi bonding.

  14. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the foreward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). He is wearing a pressure suit for this run of the M509 experiment, but other ASMU tests are done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom.

  15. Astronaut Owen Garriott trims hair of Astronaut Alan Bean

    NASA Image and Video Library

    1973-08-19

    SL3-108-1292 (19 Aug. 1973) --- Scientist-astronaut Owen K. Garriott, Skylab 3 science pilot, trims the hair of astronaut Alan L. Bean, commander, in this onboard photograph from the Skylab Orbital Workshop (OWS) in Earth orbit. Astronaut Jack R. Lousma, pilot, took this picture with a 35mm Nikon camera. Bean holds a vacuum hose to gather in loose hair. The crew of the second manned Skylab flight went on to successfully complete 59 days aboard the Skylab space station cluster in Earth orbit. Photo credit: NASA

  16. Astronaut Alan Shepard with Modular Equipment Transporter aboard KC-135

    NASA Image and Video Library

    1970-11-04

    S70-53479 (4 Nov. 1970) -- Astronaut Alan B. Shepard Jr., Apollo 14 commander, pulls the modular equipment transporter (MET) under weightless conditions aboard an Air Force KC-135 out of Patrick Air Force Base. Astronaut Edgar D. Mitchell, Apollo 14 lunar module pilot, is behind the MET. The KC-135 aircraft, flying a parabolic curve, creates a weightless environment providing a training exercise in preparation for the astronauts' extravehicular activities (EVA) on the lunar surface. This training simulates the 1/6 gravity the astronauts will encounter on the moon.

  17. Astronaut Alan Bean holds Special Environmental Sample Container

    NASA Image and Video Library

    1969-11-20

    AS12-49-7278 (19-20 Nov. 1969) --- Astronaut Alan L. Bean holds a Special Environmental Sample Container filled with lunar soil collected during the extravehicular activity (EVA) in which astronauts Charles Conrad Jr., commander, and Bean, lunar module pilot, participated. Conrad, who took this picture, is reflected in Bean's helmet visor. Conrad and Bean descended in the Apollo 12 Lunar Module (LM) to explore the lunar surface while astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) in lunar orbit. Photo credit: NASA

  18. Lightweight sodium alanate thin films grown by reactive sputtering

    SciTech Connect

    Filippi, M.; Rector, J. H.; Gremaud, R.; Setten, M. J. van; Dam, B.

    2009-09-21

    We report the preparation of sodium alanate, a promising hydrogen storage material, in a thin film form using cosputtering in a reactive atmosphere of atomic hydrogen. We study the phase formation and distribution, and the hydrogen desorption, with a combination of optical and infrared transmission spectroscopy. We show that the hydrogen desorption, the phase segregation, and the role of the dopants in these complex metal hydrides can be monitored with optical measurements. This result shows that a thin film approach can be used for a model study of technologically relevant lightweight metal hydrides.

  19. Astronaut Alan Bean works on Modular Equipment Stowage Assembly

    NASA Image and Video Library

    1969-11-19

    AS12-46-6749 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, works at the Modular Equipment Stowage Assembly (MESA) on the Apollo 12 Lunar Module (LM) during the mission's first extravehicular activity, (EVA) on Nov. 19, 1969. Astronaut Charles Conrad Jr., commander, and Bean descended in the Apollo 12 LM to explore the moon while astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) in lunar orbit.

  20. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Image and Video Library

    1973-08-27

    SL3-107-1215 (27 Aug. 1973) --- Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the forward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. One of his fellow crewmen took this photograph with a 35mm Nikon camera. Bean is strapped into the back mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). The dome area is about 22 feet in diameter and 19 feet from top to bottom. Photo credit: NASA

  1. View of Astronaut Alan Shepard inside the Freedom 7 capsule

    NASA Image and Video Library

    1961-05-05

    S88-31374 (29 April 1961) --- A close-up of astronaut Alan B. Shepard Jr. in his space suit with his helmet on inside the Mercury capsule. He is undergoing a flight simulation test with the capsule mated to the Redstone booster. This will be the first attempt to put a man into space by the U.S. aboard a Mercury spacecraft, launched atop a Redstone rocket. The suborbital trajectory will be down the Atlantic Missile Range. Photo credit: NASA or National Aeronautics and Space Administration

  2. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment

    NASA Image and Video Library

    1973-08-18

    SL3-108-1304 (July-September 1973) --- Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment in the forward dome area of the Orbital Workshop (OWS) on the space station cluster in Earth orbit. Bean is strapped in to the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). This ASMU experiment is being done in shirt sleeves. The dome area where the experiment is conducted is about 22 feet in diameter and 19 feet from top to bottom. Photo credit: NASA

  3. Astronaut Alan B. Shepard in lunar surface simulation training

    NASA Image and Video Library

    1970-07-21

    S70-46191 (July 1970) --- Astronaut Alan B. Shepard Jr., commander of the Apollo 14 lunar landing mission, participates in lunar surface training at the Kennedy Space Center (KSC). Shepard is adjusting a camera mounted to the modular equipment transporter (MET). The MET, nicknamed the "Rickshaw", will serve as a portable work bench with a place for the Apollo lunar hand tools and their carrier, three cameras, two sample container bags, a special environment sample container, spare magazines, and a lunar surface Penetrometer. Shepard is wearing an Extravehicular Mobility Unit (EMU).

  4. Astronaut Alan B. Shepard in lunar surface simulation training

    NASA Image and Video Library

    1970-07-21

    S70-46157 (July 1970) --- Astronaut Alan B. Shepard Jr., commander of the Apollo 14 lunar landing mission, participates in lunar surface simulation training at the Kennedy Space Center (KSC). The modular equipment transporter (MET) is in the left background, in the center foreground is a gnomon. The MET, nicknamed the "Rickshaw", will serve as a portable work bench with a place for the Apollo lunar hand tools and their carrier, three cameras, two sample container bags, a special environment sample container, spare magazines, and a lunar surface Penetrometer. Shepard is wearing an Extravehicular Mobility Unit (EMU).

  5. Effect of Titanium Doping of Al(111) Surfaces on Alane Formation Mobility, and Desorption

    SciTech Connect

    Chopra I. S.; Graetz J.; Chaudhuri, S.; Veyan, J.-F.; Chabal, Y. J.

    2011-07-05

    Alanes are critical intermediates in hydrogen storage reactions for mass transport during the formation of complex metal hydrides. Titanium has been shown to promote hydrogen desorption and hydrogenation, but its role as a catalyst is not clear. Combining surface infrared (IR) spectroscopy and density functional theory (DFT), the role of Ti is explored during the interaction of atomic hydrogen with Ti-doped Al(111) surfaces. Titanium is found to reduce the formation of large alanes, due to a decrease of hydrogen mobility and to trapping of small alanes on Ti sites, thus hindering oligomerization. For high doping levels ({approx}0.27 ML Ti) on Al(111), only chemisorbed AlH{sub 3} is observed on Ti sites, with no evidence for large alanes. Titanium also dramatically lowers the desorption temperature of large alanes from 290 to 190 K, due to a more restricted translational motion of these alanes.

  6. Alan Frederick Williams 25 May 1945 - 9 April 1992.

    PubMed

    Crumpton, Michael J

    2004-01-01

    Alan WIlliams is noted for his seminal contributions to the field of leucocyte membrane glycoproteins (that is, differentiation antigens). He played a leading role in the development of approaches to the purification and structural analysis of cell surface antigens. His comprehensive characterization of the structure of the rat Thy-1 antigen, as well as the application of monoclonal antibodies to the designation and subsequent isolation of multiple new leucocyte antigens, were exemplary. His discovery that Thy-1 is structurally related to immunoglobulin led directly to the concept of the immunoglobulin (Ig) superfamily, which embraced a spectrum of cell surface molecules involved in a variety of cell recognition systems. He was a very strong advocate in support of the rat as a model animal in the study of immunological phenomena. He was energetic and courageous, as well as radiating enthusiasm for immunological research, inspiring others, critically analysing accepted dogmas and setting high standards. In short, he was a brilliant research scientist.

  7. Astronaut Alan Shepard during Apollo 14 EVA on the moon

    NASA Image and Video Library

    1971-02-05

    AS14-66-9232 (5 Feb. 1971) --- Astronaut Alan B. Shepard Jr., commander of the Apollo 14 lunar landing mission, stands by the deployed United States flag on the lunar surface during the early moments of the first extravehicular activity (EVA) of the mission. Shadows of the Lunar Module (LM), astronaut Edgar D. Mitchell, lunar module pilot, and the erectable S-Band Antenna surround the scene of the third flag implanting to be performed on the lunar surface. While astronauts Shepard and Mitchell descended in the LM ?Antares? to explore the Fra Mauro region of the moon, astronaut Stuart A. Roosa, command module pilot, remained with the Command and Service Modules (CSM) ?Kitty Hawk? in lunar orbit.

  8. Borane and alane mediated hydrogen release from silane and methylsilane

    NASA Astrophysics Data System (ADS)

    Nguyen, Huyen Thi; Majumdar, D.; Leszczynski, Jerzy; Nguyen, Minh Tho

    2015-01-01

    The dehydrogenations of silanes SiH4 and CH3SiH3 in the presence of borane and alane were investigated using density functional (B3LYP) and coupled-cluster (CCSD(T)/aug-cc-pVnZ) theories. The calculated results showed that the hydrogen release reactions are more favorable in presence of BH3. Our theoretical analyses have further revealed that the addition of an extra BH3 can lead to several low energy barrier pathways. This observation is important to understand the catalytic role of BH3 in such reactions (depending on its release mechanism). Overall, silane and its alkyl derivatives can be used as effective starting materials for H2 production.

  9. Foreword: R. Alan Plumb—A brief biographical sketch and personal tribute

    NASA Astrophysics Data System (ADS)

    Sobel, Adam H.

    Raymond Alan Plumb was born on 30 March 1948 in Ripon, Yorkshire, United Kingdom. He is not known for talking about his childhood, but we do know that he liked to sing and was part of a group called the Avocets. Alan did his undergraduate degree in Manchester, obtaining his BS Physics with I Honors in 1969. He was offered a fellowship to do his PhD at Cambridge, but he had a negative reaction to a visit there and decided to stay at Manchester, where he pursued his studies in Astronomy, completing his PhD in 1972. With a highly disengaged thesis advisor, Alan was largely self-taught as a graduate student. He studied planetary atmospheres. Toward the end of his studies, Alan participated in a summer school organized by Steve Thorpe in Bangor,Wales, where he came into contact with the broader international community in geophysical fluid dynamics. Raymond Hide became particularly influential and became Alan's mentor at the UK Meteorological Office (UKMO), where Alan worked for 4 years after receiving his PhD. Another key early influence whom Alan met then was Michael McIntyre. McIntyre's interest and encouragement were very important to Alan at that early time and would continue to be so in later years, including after his move to Australia.

  10. H adsorption and the formation of alane oligomers on Al(111)

    NASA Astrophysics Data System (ADS)

    Go, Eden P.; Thuermer, Konrad; Reutt-Robey, Janice E.

    1999-09-01

    Complementary scanning tunneling microscopy and surface infrared measurements show that H reacts strongly with Al(111), producing a variety of new alane (aluminum hydride) surface species. Alane oligomers, ranging in size from the monomer to 30-mers, form through a sequence of surface etching and condensation reactions. Atomic hydrogen initiates production by extracting aluminum atoms from the surface lattice to create mobile monohydride monomers (ad-AlH), which predominate in the low-coverage regime. At higher hydrogen coverages, multihydride oligomers form in coexistence with the ad-AlH. These alane oligomers are more thermally stable, remaining on the surface at room temperature, where they are directly imaged. The mass transfer of aluminum to surface alanes is discussed in relationship to alane stoichiometry.

  11. Sir Alan Sterling Parkes: 10 September 1900 - 17 July 1990.

    PubMed

    Polge, Christopher

    2006-01-01

    Alan Parkes was one of the most influential figures in the field of reproductive biology in the twentieth century. He had a huge impact on its growth and development during that time, and the legacy of his work still remains.His research was highly innovative and original because of his imaginative and inquiring mind, which, coupled with an entrepreneurial bent, led him into several very different fields and into unchartered waters. He played a leading role in the spectacular rise of reproductive endocrinology in Britain in the 1920s and 1930s when the nature and activity of many of the reproductive processes in animals and humans and was an essential factor in the development of methods for their control. Even more pioneering was his research in low-temperature biology in the years after World War II. This was sparked off by the discovery that glycerol had a remarkable property of protecting spermatozoa against damage during freezing and storage at very low temperatures. Far-reaching applications arose from this discovery, especially in the preservation of bull semen, which led to a worldwide revolution in artificial insemination in cattle. Later, many other cells and tissues were also successfully frozen, including red blood cells, ovarian tissue and bone marrow, and a new branch of biological science, which became known as 'cryobiology', was born, Effects of deep hypothermia, including freezing, on whole animals were also investigated at that time. Having successfully launched a new area of science, it was characteristic of Alan Parkes to switch to new fields. First he became interested in the influence of pheromones on mammalian reproduction. Then, resuming a long-standing interest in comparative aspects of reproductive physiology in British wild mammals, he became involved in the work of the Nuffield Unit of Tropical Animal Ecology in Uganda, where similar studies were carried out on African animals. Even after retirement from the academic field, he was for

  12. nanoparticles

    NASA Astrophysics Data System (ADS)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J. Enrique

    2014-10-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.

  13. Astronauts Alan Bean and Charles Conrad on Lunar Surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn Five launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Their lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of rock samples. In this photograph, one of the astronauts on the Moon's surface is holding a container of lunar soil. The other astronaut is seen reflected in his helmet. Apollo 12 safely returned to Earth on November 24, 1969.

  14. Astronauts Alan Bean and Charles Conrad on Lunar Surface

    NASA Technical Reports Server (NTRS)

    1969-01-01

    The second manned lunar landing mission, Apollo 12 launched from launch pad 39-A at Kennedy Space Center in Florida on November 14, 1969 via a Saturn Five launch vehicle. The Saturn V vehicle was developed by the Marshall Space Flight Center (MSFC) under the direction of Dr. Wernher von Braun. Aboard Apollo 12 was a crew of three astronauts: Alan L. Bean, pilot of the Lunar Module (LM), Intrepid; Richard Gordon, pilot of the Command Module (CM), Yankee Clipper; and Spacecraft Commander Charles Conrad. The LM, Intrepid, landed astronauts Conrad and Bean on the lunar surface in what's known as the Ocean of Storms while astronaut Richard Gordon piloted the CM, Yankee Clipper, in a parking orbit around the Moon. Their lunar soil activities included the deployment of the Apollo Lunar Surface Experiments Package (ALSEP), finding the unmanned Surveyor 3 that landed on the Moon on April 19, 1967, and collecting 75 pounds (34 kilograms) of rock samples. In this photograph, one of the astronauts on the Moon's surface is holding a container of lunar soil. The other astronaut is seen reflected in his helmet. Apollo 12 safely returned to Earth on November 24, 1969.

  15. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Astronaut Alan B. Shepard has his blood pressure and temperate checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned space flight. The attending physician is Dr. William K. Douglas.

  16. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Astronaut Alan B. Shepard has his blood pressure and temperate checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned space flight. The attending physician is Dr. William K. Douglas.

  17. MERCURY-ATLAS (MA)-9 - SHEPARD, ALAN B., JR. ASTRONAUT - MERCURY CONTROL CENTER (MCC) - CAPE

    NASA Image and Video Library

    1963-05-16

    S63-07857 (15-16 May 1963) --- Astronaut Alan Shepard (left) and Walter C. Williams monitor progress of the Mercury Atlas 9 (MA-9) mission from Mercury Control Center, Cape Canaveral, Florida. Photo credit: NASA

  18. Astronaut Alan Shepard removing space suit on U.S. Champlain after recovery

    NASA Image and Video Library

    1961-05-05

    S88-31382 (5 May 1961) --- Astronaut Alan B. Shepard receives assistance in removing his spacesuit while on the U.S. Champlain after the recovery of his Mercury capsule. Photo credit: NASA or National Aeronautics and Space Administration

  19. LEDs/ALAN-Working To Be Good Neighbors

    NASA Astrophysics Data System (ADS)

    Adams, Robert

    2015-08-01

    ALAN (Artificial Light At Night) and LEDs have recently become major discussion topics in the areas of astronomy, light pollution, endangered species and human health to mention but a few. In years past, MH, LPS and HPS dominated night lighting with LPS and its associated narrow spectrum as the preferred source around observatories and shorelines. LEDs offer the ability to modify the spectrum, realize substantial energy savings and other associated benefits while meeting the requirements of the astronomy community.The primary concern of the different groups relates to blue light content of the LED. For astronomers, the molecular (Raleigh) scattering related to the blue light interferes with certain portions of the spectrum used for deep space studies. The ecologists studying various endangered species find blue and green light can be related to declining leatherback turtle population in certain areas of the world. Other animals ranging from bats to moths and other insects are now being studied to determine the effect of the blue light spectrum on their behavior. The impact of blue light on the human circadian rhythm and vision, especially in the older population, is being extensively studied today.This presentation will discuss the spectral power distribution (SPD) of various light sources, the performance of new LED solutions and how the SPD of these new LED’s can be adapted to address some of the issues raised by various constituencies. A discussion describing why some of the metrics used to describe standard lighting are not adequate for specifying the new LED solutions with the modified spectra will be included.Today, lighting plans and implementation are all too often based on opinions and limited data. The ensuing problems and repercussions make it imperative to collect accurate and thorough information. Data collection is now ongoing using a variety of techniques analyzing the “before” and “after” lighting results from the C of HI LED streetlight

  20. Preparation of polyaniline/sodium alanate hybrid using a spray-drying process

    SciTech Connect

    Moreira, B. R. E-mail: fabiopassador@gmail.com Passador, F. R. E-mail: fabiopassador@gmail.com Pessan, L. A. E-mail: fabiopassador@gmail.com

    2014-05-15

    Nowadays, hydrogen is highly interesting as an energy source, in particular in the automotive field. In fact, hydrogen is attractive as a fuel because it prevents air pollution and greenhouse emissions. One of the main problems with the utilization of hydrogen as a fuel is its on-board storage. The purpouse of this work was to develop a new hybrid material consisting of a polyaniline matrix with sodium alanate (NaAlH{sub 4}) using a spray-drying process. The polyaniline used for this experiment was synthesized by following a well-established method for the synthesis of the emeraldine base form of polyaniline using dodecylbenzenesulfonic acid as dopant. Micro particles of polyaniline/sodium alanate hybrids with 30 and 50 wt% of sodium alanate were prepared by using a spray-drying technique. Dilute solutions of polyaniline/sodium alanate were first prepared, 10g of the solid materials were mixed with 350 ml of toluene under stirring at room temperature for 24h and the solutions were dried using spray-dryer (Büchi, Switzerland) with 115°C of an inlet temperature. The hybrids were analyzed by differential scanning calorimetry, FT-IR and scanning electron microscopy (SEM). The addition of sodium alanate decreased the glass transition temperature of the hybrids when compared to neat polyaniline. FT-IR spectrum analysis was performed to identify the bonding environment of the synthesized material and was observed that simply physically mixture occurred between polyaniline and sodium alanate. The SEM images of the hybrids showed the formation of microspheres with sodium alanate dispersed in the polymer matrix.

  1. Preparation of polyaniline/sodium alanate hybrid using a spray-drying process

    NASA Astrophysics Data System (ADS)

    Moreira, B. R.; Passador, F. R.; Pessan, L. A.

    2014-05-01

    Nowadays, hydrogen is highly interesting as an energy source, in particular in the automotive field. In fact, hydrogen is attractive as a fuel because it prevents air pollution and greenhouse emissions. One of the main problems with the utilization of hydrogen as a fuel is its on-board storage. The purpouse of this work was to develop a new hybrid material consisting of a polyaniline matrix with sodium alanate (NaAlH4) using a spray-drying process. The polyaniline used for this experiment was synthesized by following a well-established method for the synthesis of the emeraldine base form of polyaniline using dodecylbenzenesulfonic acid as dopant. Micro particles of polyaniline/sodium alanate hybrids with 30 and 50 wt% of sodium alanate were prepared by using a spray-drying technique. Dilute solutions of polyaniline/sodium alanate were first prepared, 10g of the solid materials were mixed with 350 ml of toluene under stirring at room temperature for 24h and the solutions were dried using spray-dryer (Büchi, Switzerland) with 115°C of an inlet temperature. The hybrids were analyzed by differential scanning calorimetry, FT-IR and scanning electron microscopy (SEM). The addition of sodium alanate decreased the glass transition temperature of the hybrids when compared to neat polyaniline. FT-IR spectrum analysis was performed to identify the bonding environment of the synthesized material and was observed that simply physically mixture occurred between polyaniline and sodium alanate. The SEM images of the hybrids showed the formation of microspheres with sodium alanate dispersed in the polymer matrix.

  2. Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

    SciTech Connect

    Wang, Lin -Lin; Herwadkar, Aditi; Reich, Jason M.; Johnson, Duane D.; House, Stephen D.; Pena-Martin, Pamela; Rockett, Angus A.; Robertson, Ian M.; Gupta, Shalabh; Pecharsky, Vitalij K.

    2016-08-18

    Here, alane (AlH3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.

  3. Towards direct synthesis of alane: A predicted defect-mediated pathway confirmed experimentally

    SciTech Connect

    Wang, Lin -Lin; Herwadkar, Aditi; Reich, Jason M.; Johnson, Duane D.; House, Stephen D.; Pena-Martin, Pamela; Rockett, Angus A.; Robertson, Ian M.; Gupta, Shalabh; Pecharsky, Vitalij K.

    2016-08-18

    Here, alane (AlH3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics.

  4. Isotopic effect on the non-isothermal dehydrogenation kinetics of lithium alanates

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjay; Tiwari, Gyanendra Prasad; Krishnamurthy, Nagaiyar; Kojima, Yoshitsugu

    2017-08-01

    The isotopic effect on the dehydrogenation kinetics of lithium alanate has been studied. The desorption of hydrogen/deuterium of LiAlH4/LiAlD4 occurs in two steps below 300 °C. The deuterium desorption temperature of LiAlD4 was found to be marginally higher for both the steps as compared to hydrogen desorption of LiAlH4. The apparent activation energy of hydrogen/deuterium desorption was evaluated and found to be in the order of EaLiAlH4 >EaLiAlD4 . The higher desorption temperature of LiAlD4 has been explained on the basis the zero point energy per unit H/D atom of the alanates. The results indicate the normal isotopic effect of lithium alanate, which could be extended for the tritium.

  5. nanoparticles

    NASA Astrophysics Data System (ADS)

    Olive-Méndez, Sion F.; Santillán-Rodríguez, Carlos R.; González-Valenzuela, Ricardo A.; Espinosa-Magaña, Francisco; Matutes-Aquino, José A.

    2014-04-01

    In this work, we present the role of vanadium ions (V+5 and V+3), oxygen vacancies (VO), and interstitial zinc (Zni) to the contribution of specific magnetization for a mixture of ZnO-V2O5 nanoparticles (NPs). Samples were obtained by mechanical milling of dry powders and ethanol-assisted milling for 1 h with a fixed atomic ratio V/Zn?=?5% at. For comparison, pure ZnO samples were also prepared. All samples exhibit a room temperature magnetization ranging from 1.18?×?10-3 to 3.5?×?10-3 emu/gr. Pure ZnO powders (1.34?×?10-3 emu/gr) milled with ethanol exhibit slight increase in magnetization attributed to formation of Zni, while dry milled ZnO powders exhibit a decrease of magnetization due to a reduction of VO concentration. For the ZnO-V2O5 system, dry milled and thermally treated samples under reducing atmosphere exhibit a large paramagnetic component associated to the formation of V2O3 and secondary phases containing V+3 ions; at the same time, an increase of VO is observed with an abrupt fall of magnetization to σ?~?0.7?×?10-3 emu/gr due to segregation of V oxides and formation of secondary phases. As mechanical milling is an aggressive synthesis method, high disorder is induced at the surface of the ZnO NPs, including VO and Zni depending on the chemical environment. Thermal treatment restores partially structural order at the surface of the NPs, thus reducing the amount of Zni at the same time that V2O5 NPs segregate reducing the direct contact with the surface of ZnO NPs. Additional samples were milled for longer time up to 24 h to study the effect of milling on the magnetization; 1-h milled samples have the highest magnetizations. Structural characterization was carried out using X-ray diffraction and transmission electron microscopy. Identification of VO and Zni was carried out with Raman spectra, and energy-dispersive X-ray spectroscopy was used to verify that V did not diffuse into ZnO NPs as well to quantify O/Zn ratios.

  6. Thermochemistry of Alane Complexes for Hydrogen Storage: A Theoretical and Experimental Investigation

    SciTech Connect

    Wong, B.M.; Graetz, J.; Lacina, D.; Nielsen, I.M.B.; Allendorf, M.D.

    2011-03-30

    Knowledge of the relative stabilities of alane (AlH{sub 3}) complexes with electron donors is essential for identifying hydrogen storage materials for vehicular applications that can be regenerated by off-board methods; however, almost no thermodynamic data are available to make this assessment. To fill this gap, we employed the G4(MP2) method to determine heats of formation, entropies, and Gibbs free energies of formation for 38 alane complexes with NH{sub 3-n}R{sub n} (R = Me, Et; n = 0-3), pyridine, pyrazine, triethylenediamine (TEDA), quinuclidine, OH{sub 2-n}R{sub n} (R = Me, Et; n = 0-2), dioxane, and tetrahydrofuran (THF). Monomer, bis, and selected dimer complex geometries were considered. Using these data, we computed the thermodynamics of the key formation and dehydrogenation reactions that would occur during hydrogen delivery and alane regeneration, from which trends in complex stability were identified. These predictions were tested by synthesizing six amine-alane complexes involving trimethylamine, triethylamine, dimethylethylamine, TEDA, quinuclidine, and hexamine and obtaining upper limits of {Delta}G{sup o} for their formation from metallic aluminum. Combining these computational and experimental results, we establish a criterion for complex stability relevant to hydrogen storage that can be used to assess potential ligands prior to attempting synthesis of the alane complex. On the basis of this, we conclude that only a subset of the tertiary amine complexes considered and none of the ether complexes can be successfully formed by direct reaction with aluminum and regenerated in an alane-based hydrogen storage system.

  7. Multiscale modeling of interaction of alane clusters on Al(111) surfaces: A reactive force field and infrared absorption spectroscopy approach

    NASA Astrophysics Data System (ADS)

    Ojwang, J. G. O.; Chaudhuri, Santanu; van Duin, Adri C. T.; Chabal, Yves J.; Veyan, Jean-Francois; van Santen, Rutger; Kramer, Gert Jan; Goddard, William A.

    2010-02-01

    We have used reactive force field (ReaxFF) to investigate the mechanism of interaction of alanes on Al(111) surface. Our simulations show that, on the Al(111) surface, alanes oligomerize into larger alanes. In addition, from our simulations, adsorption of atomic hydrogen on Al(111) surface leads to the formation of alanes via H-induced etching of aluminum atoms from the surface. The alanes then agglomerate at the step edges forming stringlike conformations. The identification of these stringlike intermediates as a precursor to the bulk hydride phase allows us to explain the loss of resolution in surface IR experiments with increasing hydrogen coverage on single crystal Al(111) surface. This is in excellent agreement with the experimental works of Go et al. [E. Go, K. Thuermer, and J. E. Reutt-Robey, Surf. Sci. 437, 377 (1999)]. The mobility of alanes molecules has been studied using molecular dynamics and it is found that the migration energy barrier of Al2H6 is 2.99 kcal/mol while the prefactor is D0=2.82×10-3 cm2/s. We further investigated the interaction between an alane and an aluminum vacancy using classical molecular dynamics simulations. We found that a vacancy acts as a trap for alane, and eventually fractionates/annihilates it. These results show that ReaxFF can be used, in conjunction with ab initio methods, to study complex reactions on surfaces at both ambient and elevated temperature conditions.

  8. Multiscale modeling of interaction of alane clusters on Al(111) surfaces: a reactive force field and infrared absorption spectroscopy approach.

    PubMed

    Ojwang, J G O; Chaudhuri, Santanu; van Duin, Adri C T; Chabal, Yves J; Veyan, Jean-Francois; van Santen, Rutger; Kramer, Gert Jan; Goddard, William A

    2010-02-28

    We have used reactive force field (ReaxFF) to investigate the mechanism of interaction of alanes on Al(111) surface. Our simulations show that, on the Al(111) surface, alanes oligomerize into larger alanes. In addition, from our simulations, adsorption of atomic hydrogen on Al(111) surface leads to the formation of alanes via H-induced etching of aluminum atoms from the surface. The alanes then agglomerate at the step edges forming stringlike conformations. The identification of these stringlike intermediates as a precursor to the bulk hydride phase allows us to explain the loss of resolution in surface IR experiments with increasing hydrogen coverage on single crystal Al(111) surface. This is in excellent agreement with the experimental works of Go et al. [E. Go, K. Thuermer, and J. E. Reutt-Robey, Surf. Sci. 437, 377 (1999)]. The mobility of alanes molecules has been studied using molecular dynamics and it is found that the migration energy barrier of Al(2)H(6) is 2.99 kcal/mol while the prefactor is D(0)=2.82 x 10(-3) cm(2)/s. We further investigated the interaction between an alane and an aluminum vacancy using classical molecular dynamics simulations. We found that a vacancy acts as a trap for alane, and eventually fractionates/annihilates it. These results show that ReaxFF can be used, in conjunction with ab initio methods, to study complex reactions on surfaces at both ambient and elevated temperature conditions.

  9. MA-9 ASTRONAUT GORDON COOPER EXPLAINS CAMERA TO BACKUP PILOT ALAN SHEPARD

    NASA Technical Reports Server (NTRS)

    1963-01-01

    Astronaut L. Gordon Cooper explains the 16MM handheld spacecraft camera to his back-up pilot Astronaut Alan Shepard. The camera designed by J. R. Hereford, McDonnell Aircraft Corp., will be used by Cooper during the MA-9 mission.

  10. Challenging the Status Quo: Alan Pifer and Higher Education Reform in Colonial Nigeria

    ERIC Educational Resources Information Center

    Anyanwu, Ogechi E.

    2013-01-01

    The historiography of higher education in Nigeria has not fully accounted for Alan Pifer's crucial contributions in reforming the elitist British higher education tradition in colonial Nigeria. Through qualitative analysis of mostly primary sources acquired from the Rare Book and Manuscript Library in Columbia University, this article argues that…

  11. 77 FR 37074 - License Amendment Request From the Alan J. Blotcky Reactor Facility

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-20

    ...] [FR Doc No: 2012-15009] NUCLEAR REGULATORY COMMISSION [Docket No. 50-131; NRC-2012-0141] License Amendment Request From the Alan J. Blotcky Reactor Facility AGENCY: Nuclear Regulatory Commission. ACTION... Branch (RADB), Office of Administration, Mail Stop: TWB-05-B01M, U.S. Nuclear Regulatory...

  12. Astronaut Alan Bean looks over data acquisition camera on Skylab trainer

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut Alan L. Bean, commander for Skylab 3, the second manned Skylab mission, looks over the data acquisition camera mounted on the water tank in the upper level of the Orbital Workshop (OWS) one-G trainer at the Manned Spacecraft Center (MSC).

  13. Astronaut Alan Bean steps from ladder of Lunar Module for EVA

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, steps from the ladder of the Lunar Module to join Astronaut Charles Conrad Jr., commander, in extravehicular activity on November 19, 1969. Astronaut Ricard F. Gordon Jr., command module pilot, remained with the Command/Service Modules in lunar orbit.

  14. Astronaut Alan Bean deploys ALSEP during first Apollo 12 EVA on moon

    NASA Technical Reports Server (NTRS)

    1969-01-01

    Astronaut Alan L. Bean, Apollo 12 lunar module pilot, deploys components of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA) on the moon. The photo was made by Astronaut Charles Conrad Jr., Apollo 12 commander, using a 70mm handheld Haselblad camera modified for lunar surface usage.

  15. The Great Tunes of the Hough: Music and Song in Alan Garner's "The Stone Book Quartet "

    ERIC Educational Resources Information Center

    Godek, Sarah

    2004-01-01

    Although song and music are often elements in children's books, little critical attention has gone into examining their literary uses. Alan Garner's "The Stone Book Quartet" is an example of four texts for children in which music plays a vital role. The several snatches of traditional songs found throughout the quartet bring to life the culture of…

  16. Presidents' Panel: A Conversation with I. King Jordan, Robert Davila, and T. Alan Hurwitz

    ERIC Educational Resources Information Center

    Greenwald, Brian H.; Jordan, I. King; Davila, Robert; Hurwitz, T. Alan

    2014-01-01

    Former Gallaudet presidents: I. King Jordan and Robert Davila join current president T. Alan Hurwitz on a panel moderated by Brian H. Greenwald as they share their experience leading this institution of higher education and offer insight into the transformative changes brought about by the "Deaf President Now" movement.

  17. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Astronaut Alan B. Shepard has a thermometer in his mouth to check his temperature checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned suborbital space flight (02739); Shepard has his heart rate checked. The attending physician is Dr. William K. Douglas (02740).

  18. 2016 Summer Series - Alan Stern - The Exploration of Pluto by New Horizons

    NASA Image and Video Library

    2016-08-11

    Interplanetary exploration is essential for the long-term survival of our species. Robotic space exploration allows us to advance our knowledge of our solar system and beyond. Dr. Alan Stern will talk about the New Horizons mission to Pluto and the scientific knowledge gained through the exploration of the icy worlds at the edge of our solar system.

  19. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Image and Video Library

    1961-01-01

    S61-02740 (5 May 1961) --- Astronaut Alan B. Shepard Jr. has his heart rate checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned suborbital spaceflight. The attending physician is Dr. William K. Douglas. Photo credit: NASA or National Aeronautics and Space Administration

  20. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Image and Video Library

    1961-01-01

    S61-02749 (5 May 1961) --- Astronaut Alan B. Shepard Jr. has his blood pressure and temperature checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned spaceflight. The attending physician is Dr. William K. Douglas. Photo credit: NASA or National Aeronautics and Space Administration

  1. Challenging the Status Quo: Alan Pifer and Higher Education Reform in Colonial Nigeria

    ERIC Educational Resources Information Center

    Anyanwu, Ogechi E.

    2013-01-01

    The historiography of higher education in Nigeria has not fully accounted for Alan Pifer's crucial contributions in reforming the elitist British higher education tradition in colonial Nigeria. Through qualitative analysis of mostly primary sources acquired from the Rare Book and Manuscript Library in Columbia University, this article argues that…

  2. Astronaut Alan B. Shepard has his blood pressure and temperature checked

    NASA Technical Reports Server (NTRS)

    1961-01-01

    Astronaut Alan B. Shepard has a thermometer in his mouth to check his temperature checked prior to his Mercury-Redstone 3 (MR-3) mission, the first American manned suborbital space flight (02739); Shepard has his heart rate checked. The attending physician is Dr. William K. Douglas (02740).

  3. Presidents' Panel: A Conversation with I. King Jordan, Robert Davila, and T. Alan Hurwitz

    ERIC Educational Resources Information Center

    Greenwald, Brian H.; Jordan, I. King; Davila, Robert; Hurwitz, T. Alan

    2014-01-01

    Former Gallaudet presidents: I. King Jordan and Robert Davila join current president T. Alan Hurwitz on a panel moderated by Brian H. Greenwald as they share their experience leading this institution of higher education and offer insight into the transformative changes brought about by the "Deaf President Now" movement.

  4. OFFICIAL PORTRAIT - MERCURY-REDSTONE (MR)-3 PILOT - ASTRONAUT SHEPARD, ALAN B., JR.

    NASA Image and Video Library

    1963-03-25

    S63-02082 (5 May 1961) --- Astronaut Alan B. Shepard Jr., attired in his Mercury pressure suit, poses for a photo prior to his launch in a Mercury-Redstone 3 (MR-3) spacecraft from Cape Canaveral on a suborbital mission ? the first U.S. manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  5. Astronaut Alan Bean during news conference prior to Skylab 3 mission

    NASA Image and Video Library

    1973-06-29

    S73-30113 (30 June 1973) --- Astronaut Alan L. Bean, Skylab 3 commander, ponders a question from a newsman during the premission press conference on June 30, 1973, in the Building 1 large auditorium at Johnson Space Center. Photo credit: NASA

  6. Transmetallation between metal-only Lewis pairs: a new rhodium alane complex.

    PubMed

    Bauer, Jürgen; Braunschweig, Holger; Radacki, Krzysztof

    2012-10-28

    In this communication, synthesis of a rhodium alane Lewis adduct, [Cp(Me(3)P)(2)Rh→AlCl(3)], is reported. Given that direct synthesis using aluminium trichloride failed, a convenient transmetallation reaction was applied. The new MOLP was analysed by single crystal X-ray diffraction, multinuclear NMR spectroscopy and density functional theory calculations.

  7. Astronaut Alan Shepard - Pressure Suit - Mercury-Redstone (MR)-3 Flight

    NASA Image and Video Library

    1961-01-01

    S61-02766 (5 May 1961) --- Side view of astronaut Alan B. Shepard Jr. in his pressure suit, with helmet closed, for the Mercury-Redstone 3 (MR-3) flight, the first American manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  8. ASTRONAUT SHEPARD, ALAN - ARRIVAL - ASTRONAUT GRISSOM, VIRGIL I. (GUS) - GREETING - GRAND BAHAMA ISLAND (GBI)

    NASA Image and Video Library

    1961-05-05

    S61-02731 (5 May 1961) --- Astronaut Alan B. Shepard Jr. arrives at Grand Bahamas Island and is greeted by astronaut Virgil I. (Gus) Grissom after the first American suborbital flight. He will participate in a press conference with Grissom and Donald Slayton. Photo credit: NASA or National Aeronautics and Space Administration

  9. Astronaut Alan Shepard - Pressure Suit - Mercury-Redstone (MR)-3 flight

    NASA Image and Video Library

    1961-01-01

    S61-02755 (5 May 1961) --- Astronaut Alan B. Shepard Jr. is being helped into the lower half of his pressure suit for the Mercury-Redstone 3 (MR-3) flight, the first American manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  10. Astronaut Alan Bean looks over data acquisition camera on Skylab trainer

    NASA Image and Video Library

    1972-09-01

    S72-39256 (1972) --- Astronaut Alan L. Bean, commander for Skylab 3, the second manned Skylab mission, looks over the data acquisition camera mounted on the water tank in the upper level of the Orbital Workshop (OWS) one-G trainer at the Manned Spacecraft Center (MSC). Photo credit: NASA

  11. Closeup View - Astronaut Alan Shepard - Pressure Suit - Mercury-Redstone ( MR)-3 Flight

    NASA Image and Video Library

    1961-04-20

    S61-00220 (20 April 1961) --- Close-up view of astronaut Alan B. Shepard Jr. in his pressure suit, with helmet opened, for the Mercury-Redstone 3 (MR-3) flight, the first American manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  12. CLOSEUP VIEW - ASTRONAUT SHEPARD, ALAN - PRESSURE SUIT - MERCURY-REDSTONE (MR)-3 - CAPE

    NASA Image and Video Library

    1961-01-01

    S61-02775 (5 May 1961) --- Close-up view of astronaut Alan B. Shepard Jr. in his pressure suit, with helmet opened, for the Mercury-Redstone 3 (MR-3) flight, the first American manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  13. Astronaut Alan Shepard - Pressure Suit - Mercury-Redstone (MR)-3 Flight

    NASA Image and Video Library

    1961-04-01

    S61-02757 (5 May 1961) --- Astronaut Alan B. Shepard Jr. is being helped into his pressure suit for the Mercury-Redstone 3 (MR-3) flight, the first American manned spaceflight. Photo credit: NASA or National Aeronautics and Space Administration

  14. Astronaut Alan Bean steps from ladder of Lunar Module for EVA

    NASA Image and Video Library

    1969-11-19

    AS12-46-6729 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 lunar landing mission, steps from the ladder of the Lunar Module to join astronaut Charles Conrad Jr., commander, in extravehicular activity on Nov. 19, 1969. Astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules in lunar orbit.

  15. Astronaut Alan Bean deploys ALSEP during first Apollo 12 EVA on moon

    NASA Image and Video Library

    1969-11-19

    AS12-47-6919 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot, deploys components of the Apollo Lunar Surface Experiments Package (ALSEP) during the first Apollo 12 extravehicular activity (EVA) on the moon. The photo was made by astronaut Charles Conrad Jr., commander, using a 70mm handheld Hasselblad camera modified for lunar surface usage.

  16. Kinetics of Thermal Decomposition of Aluminum Hydride: I-non-Isothermal Decomposition Under Vacuum and in Inert Atmosphere (Argon)

    DTIC Science & Technology

    2005-05-06

    during decomposition, hydrogen gas is liberated and the initial polyhedral AlH3 crystals yield a final mix of amorphous aluminium and aluminium crystals...fastest is due to growth of the crystals. Thus, during decomposition, hydrogen gas is liberated and the initial polyhedra AlH3 crystals yield a final mix...Thermal stability; VTS ____________________________________________________________________________________ 1. Introduction Alane, AlH3 , is a

  17. Statistical Thermodynamics of Phase Transformations in Lithium Alanates with Release of Hydrogen

    NASA Astrophysics Data System (ADS)

    Zaginaichenko, S. Yu.; Matysina, Z. A.; Shchur, D. V.; Pomytkin, A. P.; Gabdullin, M. T.; Zaritskii, D. A.

    2017-02-01

    Based on the molecular and kinetic concepts, the paper presents the theory of phase transformations in lithium alanates with the release of hydrogen. The calculations are given for free energies of phases and their dependences on pressure, temperature, hydrogen concentration, and energy parameters are determined. The equations are derived for the thermodynamically-equilibrium states which determine the Pressure-Temperature-Concentration diagram and estimate the energy parameters with the use of experimental results taken from the literature. The investigation of the detected temperature/concentration dependence in crystals shows the impossibility of a complete hydrogen release from alanates. The paper contains isotherm and isopleth plots. A possibility is established for the hysteresis effect. A comparison is given to the theoretical and experimental results.

  18. Astronaut Alan Bean reads data from book while holding teleprinter tape

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, reads data from book in his right hand while holding teleprinter tape in his left hand, in the ward room of the Skylab space station's Orbital Workshop (OWS) crew quarters. This photograph was taken with a 35mm Nikon camera held by one of Bean's fellow crewmen during the 56.5 day second manned Skylab mission in Earth orbit.

  19. ASTRONAUT BEAN, ALAN L - SIMULATION - BLDG. 35 - COMMAND MODULE TRAINER - JSC

    NASA Image and Video Library

    1975-02-20

    S75-21720 (14 Feb. 1975) --- Astronaut Alan L. Bean (foreground) and cosmonaut Aleksey A. Leonov participate in Apollo-Soyuz Test Project joint crew training in Building 35 at NASA's Johnson Space Center. They are in the Apollo Command Module trainer. The training session simulated activities on the first day in Earth orbit. Bean is the commander of the American ASTP backup crew. Leonov is the commander of the Soviet ASTP first (prime) crew.

  20. Astronaut Alan Shepard stands beside large boulder found by Apollo 14 crew

    NASA Image and Video Library

    1971-02-06

    AS14-68-9414 (6 Feb. 1971) --- Astronaut Alan B. Shepard Jr., Apollo 14 commander, stands beside a large boulder on the lunar surface during the mission's second extravehicular activity (EVA), on Feb. 6, 1971. Note the lunar dust clinging to Shepard's space suit. Astronauts Shepard and Edgar D. Mitchell, lunar module pilot, explored the lunar surface while astronaut Stuart A. Roosa, command module pilot, orbited the moon in the Command and Service Modules (CSM).

  1. Astronaut Alan Shepard on U.S. Champlain after recovery of Mercury capsule

    NASA Image and Video Library

    1961-05-05

    S88-31380 (5 May 1961) --- Astronaut Alan B. Shepard Jr., strides across the deck of the U.S. Navy Carrier Champlain following an inspection of his Freedom 7 capsule. Shepard had just completed the first manned U.S. space mission, a 15-minute suborbital flight. (NASA Hq. Photo No., MR3-40) Photo credit: NASA or National Aeronautics and Space Administration

  2. Astronaut Alan Bean reads data from book while holding teleprinter tape

    NASA Image and Video Library

    1973-08-08

    SL3-111-1514 (July-September 1973) --- Astronaut Alan L. Bean, Skylab 3 commander, reads data from book in his right hand while holding teleprinter tape in his left hand, in the ward room of the Skylab space station's Orbital Workshop (OWS) crew quarters. This photograph was taken with a 35mm Nikon camera held by one of Bean's fellow crewmen during the 56.5 day second manned Skylab mission in Earth orbit. Photo credit: NASA

  3. Thermodynamic properties of molecular borane phosphines, alane amines, and phosphine alanes and the [BH(4)(-)][PH(4)(+)], [AlH(4)(-)][NH(4)(+)], and [AlH(4)(-)][PH(4)(+)] salts for chemical hydrogen storage systems from ab initio electronic structure theory.

    PubMed

    Grant, Daniel J; Dixon, David A

    2005-11-10

    The heats of formation for the molecules BH(3)PH(3), BH(2)PH(2), HBPH, AlH(3)NH(3), AlH(2)NH(2), HAlNH, AlH(3)PH(3), AlH(2)PH(2), HAlPH, AlH(4)(-), PH(3), PH(4), and PH(4)(+), as well as the diatomics BP, AlN, and AlP, have been calculated by using ab initio molecular orbital theory. The coupled cluster with single and double excitations and perturbative triples method (CCSD(T)) was employed for the total valence electronic energies. Correlation consistent basis sets were used, up through the augmented quadruple-zeta, to extrapolate to the complete basis set limit. Additional d core functions were used for Al and P. Core/valence, scalar relativistic, and spin-orbit corrections were included in an additive fashion to predict the atomization energies. Geometries were calculated at the CCSD(T) level up through at least aug-cc-pVTZ and frequencies were calculated at the CCSD(T)/aug-cc-pVDZ level. The heats of formation of the salts [BH(4)(-)][PH(4)(+)](s), [AlH(4)(-)][NH(4)(+)](s), and [AlH(4)(-)][PH(4)(+)](s) have been estimated by using an empirical expression for the lattice energy and the calculated heats of formation of the two component ions. The calculations show that both AlH(3)NH(3)(g) and [AlH(4)(-)][NH(4)(+)](s) can serve as good hydrogen storage systems that release H(2) in a slightly exothermic process. In addition, AlH(3)PH(3) and the salts [AlH(4)(-)][PH(4)(+)] and [BH(4)(-)][PH(4)(+)] have the potential to serve as H(2) storage systems. The hydride affinity of AlH(3) is calculated to be -70.4 kcal/mol at 298 K. The proton affinity of PH(3) is calculated to be 187.8 kcal/mol at 298 K in excellent agreement with the experimental value of 188 kcal/mol. PH(4) is calculated to be barely stable with respect to loss of a hydrogen to form PH(3).

  4. Hydrogen release properties of lithium alanate for application to fuel cell propulsion systems

    NASA Astrophysics Data System (ADS)

    Corbo, P.; Migliardini, F.; Veneri, O.

    In this paper the results of an experimental study on LiAlH 4 (lithium alanate) as hydrogen source for fuel cell propulsion systems are reported. The compound examined in this work was selected as reference material for light metal hydrides, because of its high hydrogen content (10.5 wt.%) and interesting desorption kinetic properties at moderate temperatures. Thermal dynamic and kinetic of hydrogen release from this hydride were investigated using a fixed bed reactor to evaluate the effect of heating procedure, carrier gas flow rate and sample form. The aim of this study was to characterize the lithium alanate decomposition through the reaction steps leading to the formation of Li 3AlH 6 and LiH. A hydrogen tank was designed and realized to contain pellets of lithium alanate as feeding for a fuel cell propulsion system based on a 2-kW Polymeric Electrolyte Fuel Cell (PEFC) stack. The fuel cell system was integrated into the power train comprising DC-DC converter, energy storage systems and electric drive for moped applications (3 kW). The experiments on the power train were conducted on a test bench able to simulate the vehicle behaviour and road characteristics on specific driving cycles. In particular the efficiencies of individual components and overall power train were analyzed evidencing the energy requirements of the hydrogen storage material.

  5. Genome Sequences of Mycobacteriophages AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo, New Members of Cluster B.

    PubMed

    Pope, Welkin H; Carbonara, Maria E; Cioffi, Hanna M; Cruz, Tyler; Dang, Brian Q; Doyle, Alexander N; Fan, Olivia H; Gallagher, Molly; Gentile, Gabrielle M; German, Brian A; Farrell, Margaret E; Gerwig, Madeline; Hunter, Kelsey L; Lefever, Virginia E; Marfisi, Nicole A; McDonnell, Jill E; Monga, Jappmann K; Quiroz, Kevin G; Pong, Alexandra C; Rimple, Patrick A; Situ, Michelle; Sohnen, Peri C; Stockinger, Annmarie N; Thompson, Paige K; Torchio, Nicole M; Toner, Chelsea L; Ulbrich, Megan C; Vohra, Neelam I; Zakir, Aala; Adkins, Nancy L; Brown, Bryony R; Churilla, Bryce M; Kramer, Zachary J; Lapin, Jonathan S; Montgomery, Matthew T; Prout, Ashley K; Grubb, Sarah R; Warner, Marcie H; Bowman, Charles A; Russell, Daniel A; Hatfull, Graham F

    2015-06-18

    AlanGrant, Baee, Corofin, OrangeOswald, and Vincenzo are newly isolated phages of Mycobacterium smegmatis mc(2)155 discovered in Pittsburgh, Pennsylvania, USA. All five phages share nucleotide similarity with cluster B mycobacteriophages but span considerable diversity with Corofin and OrangeOswald in subcluster B3, AlanGrant and Vincenzo in subcluster B4, and Baee in subcluster B5. Copyright © 2015 Pope et al.

  6. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment in the OWS

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment, as seen in this photographic reproduction taken from a television transmission made by a color television camera in the Orbital Workshop (OWS) of the Skylab space station in Earth orbit. Bean is strapped into the back-mounted, hand-controlled Automatically stabilized Maneuvering Unit (ASMU). The M509 exercise was in the forward dome area of the OWS. THe dome area is about 22 feet in diameter and 19 feet form top to bottom.

  7. Astronaut Alan Shepard near Lunar Landing Training Vehicle prior to test

    NASA Image and Video Library

    1970-12-14

    S70-56287 (14 Dec. 1970) --- Astronaut Alan B. Shepard Jr., commander of the Apollo 14 lunar landing mission, stands near a Lunar Landing Training Vehicle (LLTV) prior to a test flight at Ellington Air Force Base, Houston, on Dec. 14, 1970. Shepard will be at the controls of the Apollo 14 Lunar Module (LM) when it lands on the moon in the highlands near Fra Mauro. Astronaut Stuart A. Roosa, command module pilot, will remain with the Command and Service Modules (CSM) in lunar orbit while astronauts Shepard and Edgar D. Mitchell, lunar module pilot, descend in the LM to explore the moon.

  8. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment in the OWS

    NASA Image and Video Library

    1973-08-28

    S73-34207 (28 Aug. 1973) --- Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 astronaut Maneuvering Equipment, as seen in this photographic reproduction taken from a television transmission made by a color television camera in the Orbital Workshop (OWS) of the Skylab space station in Earth orbit. Bean is strapped into the back-mounted, hand-controlled Automatically Stabilized Maneuvering Unit (ASMU). The M509 exercise was in the forward dome area of the OWS. The dome area is about 22 feet in diameter and 19 feet from top to bottom. Photo credit: NASA

  9. Astronaut Alan Bean flies the Astronaut Maneuvering Equipment in the OWS

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Astronaut Alan L. Bean, Skylab 3 commander, flies the M509 Astronaut Maneuvering Equipment, as seen in this photographic reproduction taken from a television transmission made by a color television camera in the Orbital Workshop (OWS) of the Skylab space station in Earth orbit. Bean is strapped into the back-mounted, hand-controlled Automatically stabilized Maneuvering Unit (ASMU). The M509 exercise was in the forward dome area of the OWS. THe dome area is about 22 feet in diameter and 19 feet form top to bottom.

  10. Astronaut Alan Shepard inspects his capsule on U.S. Champlain after recovery

    NASA Image and Video Library

    1961-05-05

    S88-31384 (5 May 1961) --- Astronaut Alan B. Shepard Jr., Mercury-Redstone 3 (MR-3) pilot, is pictured near his Freedom 7 capsule during a postflight inspection aboard the U.S. Navy Carrier Champlain after the recovery of his Mercury vehicle. Earlier Shepard had completed the historical 15-minute suborbital Mercury-Redstone 3 mission, marking the U.S. inaugural manned space mission. (NASA Hq. No. 61-MR3-107 or MR3-44) Photo credit: NASA or National Aeronautics and Space Administration

  11. Metal-alane adducts with zero-valent nickel, cobalt, and iron.

    PubMed

    Rudd, P Alex; Liu, Shengsi; Gagliardi, Laura; Young, Victor G; Lu, Connie C

    2011-12-28

    Coordination complexes that pair a zero-valent transition metal (Ni, Co, Fe) and an aluminum(III) center have been prepared. They add to the few examples of structurally characterized metal alanes and are the first reported metallalumatranes. To understand the M-Al interaction and gauge the effect of varying the late metal, the complexes were characterized by X-ray crystallography, electrochemistry, UV-Vis-NIR and NMR spectroscopies, and theoretical calculations. The M-Al bond strength decreases with varying M in the order Ni > Co > Fe. © 2011 American Chemical Society

  12. Robots testing robots: ALAN-Arm, a humanoid arm for the testing of robotic rehabilitation systems.

    PubMed

    Brookes, Jack; Kuznecovs, Maksims; Kanakis, Menelaos; Grigals, Arturs; Narvidas, Mazvydas; Gallagher, Justin; Levesley, Martin

    2017-07-01

    Robotics is increasing in popularity as a method of providing rich, personalized and cost-effective physiotherapy to individuals with some degree of upper limb paralysis, such as those who have suffered a stroke. These robotic rehabilitation systems are often high powered, and exoskeletal systems can attach to the person in a restrictive manner. Therefore, ensuring the mechanical safety of these devices before they come in contact with individuals is a priority. Additionally, rehabilitation systems may use novel sensor systems to measure current arm position. Used to capture and assess patient movements, these first need to be verified for accuracy by an external system. We present the ALAN-Arm, a humanoid robotic arm designed to be used for both accuracy benchmarking and safety testing of robotic rehabilitation systems. The system can be attached to a rehabilitation device and then replay generated or human movement trajectories, as well as autonomously play rehabilitation games or activities. Tests of the ALAN-Arm indicated it could recreate the path of a generated slow movement path with a maximum error of 14.2mm (mean = 5.8mm) and perform cyclic movements up to 0.6Hz with low gain (<1.5dB). Replaying human data trajectories showed the ability to largely preserve human movement characteristics with slightly higher path length and lower normalised jerk.

  13. Professor Alan Turner (1947-2012). Specialist in Miocene-Pleistocene Carnivora, particularly Felidae and Hyaenidae and their palaeoecology

    NASA Astrophysics Data System (ADS)

    O'Regan, Hannah; Turner, Adam; Antón, Mauricio

    2014-07-01

    Alan first trained as a telecom engineer, working for the GPO (General Post Office) which later became British Telecom. He never forgot this early training and was fascinated by how things worked - always happy to take something apart and fix it (although his attempt to close a large plate glass window with a geological hammer was not one of his successes). Following a few years as an engineer, he went to Sheffield University to study archaeology as a mature student in 1973. At this time Sheffield was a hotbed of prehistory with Graeme Barker, Robin Dennell and many others contributing to a truly research-led degree (with tutorials in the pub (well, it was the 1970s)) (Fig. 1). Alan's interest in bones developed at this time, and having graduated in 1976 he went on to take a PhD, supervised by Robin Dennell, on "Aspects of the palaeoecology of large predators, including man, during the British Upper Pleistocene, with particular emphasis on predator-prey relationships" which resulted in a life-long interest in the Carnivora and particularly hyaenas. Following his PhD, Alan moved to the Environmental Archaeology Unit at York to undertake a Science Research Council project on the morphometrics of domestic cattle and pigs from Coppergate and other major urban excavations in the city. Faced with a lot of measurements and statistics, Alan retained his interest in the animals themselves. The project also confirmed to Alan that prehistory was his metier, rather than the historic periods. Former York colleagues still fondly recall Alan's dry wit, and the day that he successfully put the irritating lab telephone beyond use with no externally visible trace of damage.

  14. Apollo 12 Mission image - Alan Bean unloads ALSEP RTG fuel element

    NASA Image and Video Library

    1969-11-19

    AS12-46-6790 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot, is photographed at quadrant II of the Lunar Module (LM) during the first Apollo 12 extravehicular activity (EVA) on the moon. This picture was taken by astronaut Charles Conrad Jr., commander. Here, Bean is using a fuel transfer tool to remove the fuel element from the fuel cask mounted on the LM's descent stage. The fuel element was then placed in the Radioisotope Thermoelectric Generator (RTG), the power source for the Apollo Lunar Surface Experiments Package (ALSEP) which was deployed on the moon by the two astronauts. The RTG is next to Bean's right leg. While astronauts Conrad and Bean descended in the LM "Intrepid" to explore the Ocean of Storms region of the moon, astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) "Yankee Clipper" in lunar orbit.

  15. Anisotropic storage medium development in a full-scale, sodium alanate-based, hydrogen storage system

    DOE PAGES

    Jorgensen, Scott W.; Johnson, Terry A.; Payzant, E. Andrew; ...

    2016-06-11

    Deuterium desorption in an automotive-scale hydrogen storage tube was studied in-situ using neutron diffraction. Gradients in the concentration of the various alanate phases were observed along the length of the tube but no significant radial anisotropy was present. In addition, neutron radiography and computed tomography showed large scale cracks and density fluctuations, confirming the presence of these structures in an undisturbed storage system. These results demonstrate that large scale storage structures are not uniform even after many absorption/desorption cycles and that movement of gaseous hydrogen cannot be properly modeled by a simple porous bed model. In addition, the evidence indicatesmore » that there is slow transformation of species at one end of the tube indicating loss of catalyst functionality. These observations explain the unusually fast movement of hydrogen in a full scale system and shows that loss of capacity is not occurring uniformly in this type of hydrogen-storage system.« less

  16. Anisotropic storage medium development in a full-scale, sodium alanate-based, hydrogen storage system

    SciTech Connect

    Jorgensen, Scott W.; Johnson, Terry A.; Payzant, E. Andrew; Bilheux, Hassina Z.

    2016-06-11

    Deuterium desorption in an automotive-scale hydrogen storage tube was studied in-situ using neutron diffraction. Gradients in the concentration of the various alanate phases were observed along the length of the tube but no significant radial anisotropy was present. In addition, neutron radiography and computed tomography showed large scale cracks and density fluctuations, confirming the presence of these structures in an undisturbed storage system. These results demonstrate that large scale storage structures are not uniform even after many absorption/desorption cycles and that movement of gaseous hydrogen cannot be properly modeled by a simple porous bed model. In addition, the evidence indicates that there is slow transformation of species at one end of the tube indicating loss of catalyst functionality. These observations explain the unusually fast movement of hydrogen in a full scale system and shows that loss of capacity is not occurring uniformly in this type of hydrogen-storage system.

  17. Reducing the Harms of College Student Drinking: How Alan Marlatt Changed Approaches, Outcomes, and the Field

    PubMed Central

    Kilmer, Jason R.; Palmer, Rebekka S.; Cronce, Jessica M.; Logan, Diane E.

    2015-01-01

    In this article, we discuss Alan Marlatt’s contributions to the prevention and reduction of alcohol-related harms among college students. We consider Alan’s early research that later led to the development and evaluation of college student drinking programs, and examine Alan’s impact, both directly and indirectly through those he mentored and trained, as a scientist-practitioner. We review the recognition of the efficacy of Alan’s programs, including the Alcohol Skills Training Program (ASTP) and Brief Alcohol Screening and Intervention for College Students (BASICS), in addition to extensions of these interventions in more recent studies. Finally, we discuss how Alan’s work influences interventions with college student drinkers today, and how future directions will continue to be informed by his vision and values. PMID:25774117

  18. Anisotropic storage medium development in a full-scale, sodium alanate-based, hydrogen storage system

    SciTech Connect

    Jorgensen, Scott W.; Johnson, Terry A.; Payzant, E. Andrew; Bilheux, Hassina Z.

    2016-06-11

    Deuterium desorption in an automotive-scale hydrogen storage tube was studied in-situ using neutron diffraction. Gradients in the concentration of the various alanate phases were observed along the length of the tube but no significant radial anisotropy was present. In addition, neutron radiography and computed tomography showed large scale cracks and density fluctuations, confirming the presence of these structures in an undisturbed storage system. These results demonstrate that large scale storage structures are not uniform even after many absorption/desorption cycles and that movement of gaseous hydrogen cannot be properly modeled by a simple porous bed model. In addition, the evidence indicates that there is slow transformation of species at one end of the tube indicating loss of catalyst functionality. These observations explain the unusually fast movement of hydrogen in a full scale system and shows that loss of capacity is not occurring uniformly in this type of hydrogen-storage system.

  19. Moral absolutism and abortion: Alan Donagan on the hysterectomy and craniotomy cases.

    PubMed

    Reynolds, Terrence

    1985-07-01

    Reynolds argues that the nonconsequentialist moral theory proposed by Alan Donagan in his book The Theory of Morality (University of Chicago Press; 1977) does not resolve the cases in which craniotomy or removal of a cancerous uterus appears necessary to save the life of a pregnant woman. Donagan's absolute prohibition against the murder of the innocent and his rejection of the principle of double effect have led him to view the fetus as a pursuer or assailant or to assert the theory of proleptic agreement--that in risk taking ventures the parties may agree that killing one person to save the lives of the others will be accepted. Reynolds holds these arguments to be inapplicable in therapeutic abortions involving craniotomy or hysterectomy and concludes that Donagan's absolutist theory must be reexamined.

  20. First-principles study of hydrogen vacancies in sodium alanate with Ti substitution.

    PubMed

    Wang, Hao; Tezuka, Akinori; Ogawa, Hiroshi; Ikeshoji, Tamio

    2010-05-26

    In order to clarify the effect of hydrogen vacancies on the stability and structure of sodium alanate, NaAlH(4), with and without Ti substitution for Al, first-principles electronic structure calculations were carried out. The relative thermodynamic stability of the Ti dopant and the H vacancy in a supercell was obtained. For the Ti-doped Na(16)Al(16)H(64) supercell calculations, it was preferable to perform the initial substitution with a cluster of TiAlH(n). We showed that substitution of a Ti atom for an Al atom in Na(16)Al(15)TiH(63) with H vacancies increases the stability of the structure. A density of states analysis revealed weakening of the bond strength corresponding to increase in the bond length.

  1. Growth Mechanisms of Aluminum Dots Deposited by Laser-induced Decomposition of Trimethylamine Alane

    NASA Astrophysics Data System (ADS)

    Tonneau, Didier; Thuron, Frédéric; Correia, Antonio; Bouree, Jean; Pauleau, Yves

    1998-09-01

    Aluminum dots have been deposited by thermal decomposition of trimethylamine alane (TMAA) on silicon substrates irradiated with a tightly focused argon ion laser beam (λ=514 nm). Carbon free Al deposits containing less than 5 at.% of impurities (mainly oxygen) detected by Auger Electron Spectroscopy were grown. The growth kinetics of Al dots was investigated as a function of TMAA pressure and laser-induced temperature. The deposition of dots occurred at a laser-induced temperature as low as 210°C. The TMAA decomposition was thermally activated (activation energy of 18 kcal/mole) and the deposition rate at 300°C was equal to 2 µm/s. The effects of H2 or He (used as buffer gases) in the gas phase on the growth kinetics of dots was also studied. The growth mechanisms of dots are discussed and proposed on the basis of the results of this kinetic study.

  2. Astronaut Alan Shepard is rescued by helicopter at end of MR-3 flight

    NASA Image and Video Library

    1961-05-05

    S88-31376 (5 May 1961) --- Astronaut Alan B. Shepard Jr., pilot of the Mercury-Redstone 3 (MR-3) suborbital spaceflight, is retrieved by a helicopter from the USS Lake Champlain during recovery operations in the western Atlantic Ocean. Shepard and the Mercury spacecraft designated the ?Freedom 7? (floating in water below) were flown to the deck of the recovery ship within 11 minutes of splashdown. MR-3 was the United States? first manned space mission. The spacecraft attained a maximum speed of 5,180 miles per hour, reached an altitude of 116 1/2 statute miles, and landed 302 statute miles downrange from Cape Canaveral, Florida. The suborbital mission lasted 15 minutes and 22 seconds. Photo credit: NASA or National Aeronautics and Space Administration

  3. Astronaut Alan Shepard - U.S.S. Champlain - Post-Recovery Mercury Capsule

    NASA Image and Video Library

    1961-05-05

    S61-02727 (5 May 1961) --- Astronaut Alan B. Shepard is seen on the deck of the USS Lake Champlain after the recovery of his Mercury capsule in the western Atlantic Ocean. Shepard and the Mercury spacecraft designated the ?Freedom 7? were flown to the deck of the recovery ship within 11 minutes of splashdown. MR-3 was the United States? first manned space mission. The spacecraft attained a maximum speed of 5,180 miles per hour, reached an altitude of 116 1/2 statute miles, and landed 302 statute miles downrange from Cape Canaveral, Florida. The suborbital mission lasted 15 minutes and 22 seconds. Photo credit: NASA or National Aeronautics and Space Administration

  4. An Interview with Alan J. Hovestadt: AAMFT Past President and Long-Time Marriage and Family Counselor Educator

    ERIC Educational Resources Information Center

    Juhnke, Gerald A.; Sunich, Michael F.; Coll, Kenneth M.; Lebron-Striker, Maritza

    2009-01-01

    Alan J. Hovestadt, EdD, is the immediate past president of the 24,000 member American Association for Marriage and Family Therapy (AAMFT) and a long-time IAMFC member who served as an IAMFC founding board member when American Counseling Association (ACA) first granted International Association of Marriage and Family Counselors (IAMFC) divisional…

  5. An Interview with Alan J. Hovestadt: AAMFT Past President and Long-Time Marriage and Family Counselor Educator

    ERIC Educational Resources Information Center

    Juhnke, Gerald A.; Sunich, Michael F.; Coll, Kenneth M.; Lebron-Striker, Maritza

    2009-01-01

    Alan J. Hovestadt, EdD, is the immediate past president of the 24,000 member American Association for Marriage and Family Therapy (AAMFT) and a long-time IAMFC member who served as an IAMFC founding board member when American Counseling Association (ACA) first granted International Association of Marriage and Family Counselors (IAMFC) divisional…

  6. Black and Conservative: Finding a Place. A Symposium on Alan L. Keyes'"Masters of the Dream".

    ERIC Educational Resources Information Center

    Ervin, Clark Kent; And Others

    1995-01-01

    Presents commentaries from Clark Kent Ervin, A. J. Williams-Meyers, and Paul T. Murray on Alan L. Keyes'"Masters of the Dream: The Strength and Betrayal of Black America" (1995). They respond to Keyes' controversial assertions, among which is that the Great Society movement and liberalism have undermined black progress that today's…

  7. Black and Conservative: Finding a Place. A Symposium on Alan L. Keyes'"Masters of the Dream".

    ERIC Educational Resources Information Center

    Ervin, Clark Kent; And Others

    1995-01-01

    Presents commentaries from Clark Kent Ervin, A. J. Williams-Meyers, and Paul T. Murray on Alan L. Keyes'"Masters of the Dream: The Strength and Betrayal of Black America" (1995). They respond to Keyes' controversial assertions, among which is that the Great Society movement and liberalism have undermined black progress that today's…

  8. Discovering the Optimal Route for Alane Synthesis on Ti doped Al Surfaces Using Density Functional Theory Based Kinetic Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Karim, Altaf; Muckerman, James T.

    2010-03-01

    Issues such as catalytic dissociation of hydrogen and the mobility of alane species on Ti-doped Al surfaces are major challenges in the synthesis of aluminum hydride. Our recently developed modeling framework (DFT-based KMC simulation) enabled us to study the steady-state conditions of dissociative adsorption of hydrogen, its diffusion, and its reaction with Al adatoms leading to the formation of alane species on Ti-doped Al surfaces. Our studies show that the doping of Ti atoms in the top layer of Al surfaces significantly reduces the mobility of alane species. On the other hand, the doping of Ti atoms beneath the top layer of Al surfaces enhances the mobility of alane species. The arrangement of dopant Ti atoms in different layers not only affects the diffusion barriers of alane species but it also affects hydrogen dissociation barriers when Ti-Ti pairs are arranged in different ways in the top layer. Using our theoretical methods, we identified a few configurations of dopant Ti atoms having lower barriers for alane diffusion and hydrogen dissociation. Further, we discovered the optimal values of Ti concentration, temperature, and pressure under which the rate of alane formation is maximized.

  9. The Society of Brains: How Alan Turing and Marvin Minsky Were Both Right

    NASA Astrophysics Data System (ADS)

    Struzik, Zbigniew R.

    2015-04-01

    In his well-known prediction, Alan Turing stated that computer intelligence would surpass human intelligence by the year 2000. Although the Turing Test, as it became known, was devised to be played by one human against one computer, this is not a fair setup. Every human is a part of a social network, and a fairer comparison would be a contest between one human at the console and a network of computers behind the console. Around the year 2000, the number of web pages on the WWW overtook the number of neurons in the human brain. But these websites would be of little use without the ability to search for knowledge. By the year 2000 Google Inc. had become the search engine of choice, and the WWW became an intelligent entity. This was not without good reason. The basis for the search engine was the analysis of the ’network of knowledge’. The PageRank algorithm, linking information on the web according to the hierarchy of ‘link popularity’, continues to provide the basis for all of Google's web search tools. While PageRank was developed by Larry Page and Sergey Brin in 1996 as part of a research project about a new kind of search engine, PageRank is in its essence the key to representing and using static knowledge in an emergent intelligent system. Here I argue that Alan Turing was right, as hybrid human-computer internet machines have already surpassed our individual intelligence - this was done around the year 2000 by the Internet - the socially-minded, human-computer hybrid Homo computabilis-socialis. Ironically, the Internet's intelligence also emerged to a large extent from ‘exploiting’ humans - the key to the emergence of machine intelligence has been discussed by Marvin Minsky in his work on the foundations of intelligence through interacting agents’ knowledge. As a consequence, a decade and a half decade into the 21st century, we appear to be much better equipped to tackle the problem of the social origins of humanity - in particular thanks to the

  10. Functional anion concept: effect of fluorine anion on hydrogen storage of sodium alanate.

    PubMed

    Yin, Li-Chang; Wang, Ping; Kang, Xiang-Dong; Sun, Cheng-Hua; Cheng, Hui-Ming

    2007-03-28

    Doping NaAlH(4) with Ti-catalyst has produced a promising hydrogen storage system that can be reversibly operated at moderate temperature conditions. Of the various dopant precursors, TiCl(3) was well recognized due to its pronounced catalytic effect on the reversible dehydrogenation processes of sodium aluminium hydrides. Quite recently we experimentally found that TiF(3) was even better than TiCl(3) in terms of the critical hydrogen storage properties of the doped hydrides, in particular the dehydriding performance at Na(3)AlH(6)/NaH + Al step at moderate temperature. We present here the DFT calculation results of the TiF(3) or TiCl(3) doped Na(3)AlH(6). Our computational studies have demonstrated that F(-) and Cl(-) anions differ substantially from each other with regard to the state and function in the doped sodium aluminium hydride. In great contrast to the case of chloride doping where Cl(-) anion constitutes the "dead weight" NaCl, the fluoride doping results in a substitution of H(-) by F(-) anion in the hydride lattice and accordingly, a favorable thermodynamics adjustment. These results well explain the observed dehydriding performance associated with TiF(3)/TiCl(3)-doping. More significantly, the coupled computational and experimental efforts allow us to put forward a "functional anion" concept. This renews the current mechanism understanding in the catalytically enhanced sodium alanate.

  11. Developmental and environmental influences on physiology and behavior--2014 Alan N. Epstein Research Award.

    PubMed

    Tamashiro, Kellie L K

    2015-12-01

    Environmental factors acting during development of an individual may influence future health and disease susceptibility. Stressors, including altered diet, psychosocial stress, and immune challenge, during gestation can have negative consequences on the intrauterine environment and increase disease susceptibility of the developing fetus. The long-term effects on offspring have been observed in humans and include greater susceptibility to psychiatric disease, such as depression and anxiety disorders, and adverse metabolic conditions including obesity, diabetes and cardiovascular disease. Studies in my laboratory use rodent models and incorporate a multilevel approach to determine the behavioral, physiological, and neurobiological correlates of disease development as a consequence of early life stressors. The road I took in developing this research program was a rather circuitous one and navigating that path would not have been possible without the many mentors, colleagues, fellows and students who provided critical support. Although my name appears on the plaque of the Alan N. Epstein Research Award, I share this with all those I had the privilege of working with along that road, as briefly summarized in this article. Copyright © 2015 Elsevier Inc. All rights reserved.

  12. Developmental and Environmental Influences on Physiology and Behavior – 2014 Alan N. Epstein Research Award

    PubMed Central

    Tamashiro, Kellie L. K.

    2015-01-01

    Environmental factors acting during development of an individual may influence future health and disease susceptibility. Stressors, including altered diet, psychosocial stress, immune challenge, during gestation can have negative consequences on the intrauterine environment and increase disease susceptibility of the developing fetus. The long-term effects on offspring have been observed in humans and include greater susceptibility to psychiatric disease, such as depression and anxiety disorders, and adverse metabolic conditions including obesity, diabetes and cardiovascular disease. Studies in my laboratory use rodent models and incorporate a multilevel approach to determine the behavioral, physiological, and neurobiological correlates of disease development as a consequence of early life stressors. The road I took in developing this research program was a rather circuitous one and navigating that path would not have been possible without the many mentors, colleagues, fellows and students who provided critical support. Although my name appears on the plaque of the Alan N. Epstein Research Award, I share this with all those I had the privilege of working with along that road, as briefly summarized in this article. PMID:26291266

  13. Determining the structure of Ac-AlanLysH^+ in vacuo: computational spectroscopy using DFT

    NASA Astrophysics Data System (ADS)

    Rossi, Mariana; Blum, Volker; Kupser, Peter; von Helden, Gert; Bierau, Frauke; Meijer, Gerard; Scheffler, Matthias

    2010-03-01

    Well defined secondary structure motifs (e.g., helices) in polypeptides can be systematically studied in vacuo, offering a unique ``clean room" condition to quantify the stabilizing intramolecular interactions. Here we address theoretically the structure of alanine polypeptides Ac-Alan-LysH^+ (n=5,10,15), for which gas-phase helical structure was indicated in experiment [1]. Using van der Waals (vdW) corrected [2] Density Functional Theory (DFT), we present vibrational spectra and compare to room temperature multiple photon IR spectroscopy data obtained at the FELIX free electron laser. For the longer molecules (n=10,15) α-helical models provide good qualitative agreement (theory vs. experiment) already in the harmonic approximation. For Ac-Ala5LysH^+, the predicted lowest energy conformer (``g-1'') in vdW corrected DFT (PBE, B3LYP, revPBE) is not a simple helix. However, the harmonic free energy suggests that g-1 and the lowest-energy α-helical conformers are energetically close at 300 K, and thus might all coexist in experiment. Consistently, their calculated vibrational spectra agree with experiment, but only if anharmonic effects are included by explicit molecular dynamics simulations. [1] R. Hudgins et al., JACS 120, 12974 (1998) [2] A. Tkatchenko, M. Scheffler, PRL 102, 073005 (2009)

  14. Pi bonding and negative hyperconjugation in mono-, di-, and triaminoborane, -alane, -gallane, and -indane.

    PubMed

    Kormos, Bethany L; Cramer, Christopher J

    2003-10-20

    A systematic quantum chemical investigation of mono-, di-, and triaminoborane, -alane, -gallane, and -indane is carried out to determine quantitatively the effects of pi bonding and negative hyperconjugation on structures, energetics, and rotational barriers in these systems. Pi bonding plays a significant role in the aminoborane compounds, but becomes rapidly less significant in the aminoalanes, -gallanes, and -indanes. For each main-group metal X investigated, X-N rotational barriers are found to be essentially equal depending only on the number of remaining in-plane amino groups. The contribution of negative hyperconjugation to reducing rotational barriers, as assessed from natural bond orbital (NBO) delocalization energies, is independent of the pyramidalization of the out-of-plane amino group, and is also dependent only on the number of rotated groups. Optimized tris[bis(trimethylsilyl)amino]-substituted structures of boron, aluminum, gallium, and indium are found to compare quite well with available experimental structural data, and exhibit X-N torsion angles that are independent of the central metal atom.

  15. Reactions of organyl and silyl alanes with 1,3,4,5,6-pentamethyl-2-aminoborazine.

    PubMed

    Fan, Maomin; Duesler, Eileen N; Nöth, Heinrich; Paine, Robert T

    2010-03-15

    The reactions of (Me(3)Si)(3)Al, Me(3)Al, Et(3)Al, and i-Bu(3)Al with 1,3,4,5,6-pentamethyl-2-aminoborazine have been examined. An amine alane adduct (Me(3)Si)(3)Al.NH(2)B(3)(Me)(2)N(3)Me(3) (1) and several elimination products [(Me(3)Si)(2)AlN(H)B(3)(Me)(2)N(3)Me(3)](2) (2), [(Me(3)SiAl)(4)(Me(3)SiN)(3)NH] (3), [Me(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (4), [Et(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (5), and [i-Bu(2)AlN(H) B(3)(Me)(2)N(3)Me(3)](2) (6) have been isolated. Compounds 1, 2, 4-6 have been spectroscopically characterized, and single crystal X-ray diffraction structure determinations have been completed for 1-4 and 6. The molecular chemistry provides insight into the reaction of Me(3)Al and 1,3,5-N-trimethyl-2,4,6-B-triaminoborazine that, upon pyrolysis, produces AlN/BN composite ceramic materials.

  16. Elusive silane-alane complex [Si-H⋅⋅⋅Al]: isolation, characterization, and multifaceted frustrated Lewis pair type catalysis.

    PubMed

    Chen, Jiawei; Chen, Eugene Y-X

    2015-06-01

    The super acidity of the unsolvated Al(C6F5)3 enabled isolation of the elusive silane-alane complex [Si-H⋅⋅⋅Al], which was structurally characterized by spectroscopic and X-ray diffraction methods. The Janus-like nature of this adduct, coupled with strong silane activation, effects multifaceted frustrated-Lewis-pair-type catalysis. When compared with the silane-borane system, the silane-alane system offers unique features or clear advantages in the four types of catalytic transformations examined in this study, including: ligand redistribution of tertiary silanes into secondary and quaternary silanes, polymerization of conjugated polar alkenes, hydrosilylation of unactivated alkenes, and hydrodefluorination of fluoroalkanes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. From Mercury to Apollo: astronaut Alan Shepard reflects on life support and other space issues [interview by Winston Huff].

    PubMed

    Shepard, A

    1995-01-01

    Alan Shepard was one of the original Mercury astronauts. He became the first American in space on May 5, 1961, in the Freedom 7 capsule, during a 15 minute suborbital trip reaching 115 miles altitude and 302 miles down the Atlantic tracking range. Grounded by an inner ear problem, he served as Chief of the Astronaut Office for several years. After an operation to correct the problem, he commanded the Apollo 14 moon mission in 1971. He retired as a Rear Admiral in 1974. Here, Alan Shepard offers his views on life support comedies and tragedies, going back to the moon, future drivers of the manned space flight program, the benefits of the space program, joint NASA and Russia missions, how his NASA experience affected his personal life, and the profitability of working with NASA.

  18. Apollo 12 Mission image - Dark view of Astronaut Alan L. Bean climbing down the ladder of the Lunar Module (LM)

    NASA Image and Video Library

    1969-11-19

    AS12-46-6728 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 mission, is about to step off the ladder of the Lunar Module to join astronaut Charles Conrad Jr., mission commander, in extravehicular activity (EVA). Conrad and Bean descended in the Apollo 12 LM to explore the moon while astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules in lunar orbit.

  19. Apollo 12 Mission image - Dark view of Astronaut Alan L. Bean climbing down the ladder of the Lunar Module (LM)

    NASA Image and Video Library

    1969-11-19

    AS12-46-6726 (19 Nov. 1969) --- Astronaut Alan L. Bean, lunar module pilot for the Apollo 12 mission, starts down the ladder of the Lunar Module (LM) to join astronaut Charles Conrad Jr., mission commander, in extravehicular activity (EVA). While astronauts Conrad and Bean descended in the LM "Intrepid" to explore the Ocean of Storms region of the moon, astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) "Yankee Clipper" in lunar orbit.

  20. Hydrogen Storage Solutions in Support of DoD Warfighter Portable Power Applications

    DTIC Science & Technology

    2009-04-01

    Table 3 have a high volumetric hydro- gen capacity. For example Alane ( AlH3 ) has twice the hydrogen capacity of liquid hydrogen, making it a good...MHCoE is AlH3 . This material is able to readily release 10 wt% hydrogen at practical conditions but it requires more than 100,000 atmospheres of pressure...and so far have shown some success using both electrochemical and chemical synthesis methods, respectively.[6] While the materials being developed by

  1. Materials Data on AlH3 (SG:167) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  2. Formation and decomposition of AlH3 in the aluminum-hydrogen system

    NASA Astrophysics Data System (ADS)

    Saitoh, H.; Machida, A.; Katayama, Y.; Aoki, K.

    2008-10-01

    The pressure-temperature diagram of hydrogen-aluminum system was determined for a pressure range of 0-10GPa and a temperature range of 27-800°C by in situ x-ray diffraction measurements. Pristine aluminum was hydrogenated to trihydride at 8.9GPa and 600°C. The cyclic formation and decomposition of the hydride resulted in lowering of the hydrogenation conditions down to 4.9GPa and 330°C. Transparent single crystals were recovered at ambient conditions.

  3. Materials Data on AlH3 (SG:58) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  4. The effect of the NH2 substituent on NH3: hydrazine as an alternative for ammonia in hydrogen release in the presence of boranes and alanes.

    PubMed

    Vinh-Son, Nguyen; Swinnen, Saartje; Matus, Myrna H; Nguyen, Minh Tho; Dixon, David A

    2009-08-14

    Potential energy surfaces for H(2) release from hydrazine interacting with borane, alane, diborane, dialane and borane-alane were constructed from MP2/aVTZ geometries and zero point energies with single point energies at the CCSD(T)/aug-cc-pVTZ level. With one borane or alane molecule, the energy barrier for H(2)-loss of approximately 38 or 30 kcal mol(-1) does not compete with the B-N or Al-N bond cleavage ( approximately 30 or approximately 28 kcal mol(-1)). The second borane or alane molecule can play the role of a bifunctional catalyst. The barrier energy for H(2)-elimination is reduced from 38 to 23 kcal mol(-1), or 30 to 20 kcal mol(-1) in the presence of diborane or dialane, respectively. The mixed borane-alane dimer reduces the barrier energy for H(2) release from hydrazine to approximately 17 kcal mol(-1). A systematic comparison with the reaction pathways from ammonia borane shows that hydrazine could be an alternative for ammonia in producing borane amine derivatives. The results show a significant effect of the NH(2) substituent on the relevant thermodynamics. The B-N dative bond energy of 31 kcal mol(-1) in NH(2)NH(2)BH(3) is approximately 5 kcal mol(-1) larger than that of the parent BH(3)NH(3). The higher thermodynamic stability could allow hydrazine-borane to be used as a material for certain energetic H(2) storage applications.

  5. Hydrogen storage in calcium alanate: First-principles thermodynamics and crystal structures

    NASA Astrophysics Data System (ADS)

    Wolverton, Christopher; Ozoliņš, Vidvuds

    2007-02-01

    Using first-principles density functional theory (DFT) calculations, we study the thermodynamics and crystal structure of calcium alanate, Ca(AlH4)2 , and its decomposition products CaAlH5 , CaH2 , and CaAl2 . Using a large database of AB2C8 and ABC5 structure types, we perform nearly 200 DFT calculations in an effort to predict the crystal structures of the Ca(AlH4)2 and CaAlH5 phases. For the low-energy T=0K phases, we perform DFT frozen-phonon calculations to ascertain the zero-point and vibrational entropy contributions to the thermodynamics of decomposition. We find the following: (i) For Ca(AlH4)2 , we confirm the previously predicted CaB2F8 -type structure as the stable phase. In addition, we uncover several phases (e.g., β-ThMo2O8 -type, AgAu2F8 -type, and PbRe2O8 -type) very competitive in energy with the ground state structure. (ii) For CaAlH5 , we find the stable structure type to be the recently observed α'-SrAlF5 -type, with UTlF5 -type, SrFeF5 -type and BaGaF5 -type structures being close in energy to the ground state. (iii) In agreement with recent experiments, our calculations show that the decomposition of Ca(AlH4)2 is divided into a weakly exothermic step [Ca(AlH4)2→CaAlH5+Al+3/2H2] , a weakly endothermic step [CaAlH5→CaH2+Al+3/2H2] , and a strong endothermic step [CaH2+2Al→CaAl2+H2] . (iv) Including static T=0K energies, zero-point energies, and the dynamic contributions of H2 gas, the DFT-calculated ΔH values for the first two decomposition steps ( -9 and +26kJ/mol H2 at the observed decomposition temperatures Ttilde 127 and 250°C , respectively) agree well with the experimental values recently reported ( -7 and +32kJ/mol H2 ). Only the second step [CaAlH5/CaH2] has thermodynamics near the targeted range that might make a suitable on-board hydrogen storage reaction for hydrogen-fueled vehicles. (v) Comparing the enthalpies for final stage of decomposition [ CaH2+2Al→CaAl2+H2 , ΔH=72kJ/mol H2 ] with the pure decomposition of CaH2

  6. Effect of Ti Dopant on Surface Diffusion of Isolated Alane Species: A Comparison between Al (111) and Al (100) surfaces

    NASA Astrophysics Data System (ADS)

    Karim, Altaf; Muckerman, James

    2009-03-01

    Our density functional theory-based kinetic Monte Carlo simulations show that an embedded Ti atom creates a well in the potential energy surfaces of Al(111) and Al(100) as probed by hydrogen and other isolated alane species. Hydrogen adatoms become trapped around Ti atoms on an Al(111) surface, whereas Al adatoms do not exhibit any significant effect of the potential energy well created by the Ti atoms. In contrast to the case of Al(111), Al adatoms on an Al(100) surface also become trapped around the Ti atoms for a longer period of time compared to the hydrogen adatoms on this surface. Therefore, Ti sites on Al(100) become poisoned by the presence of Al adatoms around them for long periods of time, thereby blocking further dissociative adsorption of hydrogen. The overall diffusion of Al adatoms on an Al(100) surface is significantly lower compared to the Al(111) surface. This fact suggests that the Ti-doped Al(111) surface is perhaps more conducive to the production of alane species than the Ti-doped Al(100) surface despite its higher activation barrier for the dissociation of molecular hydrogen.

  7. Apollo 12 Mission image - Astronaut Alan L. Bean,lunar module pilot,and two U.S. spacecraft

    NASA Image and Video Library

    1969-11-20

    AS12-48-7134 (20 Nov. 1969) --- This unusual photograph, taken during the second Apollo 12 extravehicular activity (EVA), shows two U.S. spacecraft on the surface of the moon. The Apollo 12 Lunar Module (LM) is in the background. The unmanned Surveyor 3 spacecraft is in the foreground. The Apollo 12 LM, with astronauts Charles Conrad Jr. and Alan L. Bean aboard, landed about 600 feet from Surveyor 3 in the Ocean of Storms. The television camera and several other pieces were taken from Surveyor 3 and brought back to Earth for scientific examination. Here, Conrad examines the Surveyor's TV camera prior to detaching it. Astronaut Richard F. Gordon Jr. remained with the Apollo 12 Command and Service Modules (CSM) in lunar orbit while Conrad and Bean descended in the LM to explore the moon. Surveyor 3 soft-landed on the moon on April 19, 1967.

  8. A requiem for whole brain death: a response to D. Alan Shewmon's 'the brain and somatic integration'.

    PubMed

    Potts, M

    2001-10-01

    Alan Shewmon's article, 'The brain and somatic integration: Insights into the standard biological rationale for equating "brain death" with death' (2001), strikes at the heart of the standard justification for whole brain death criteria. The standard justification, which I call the 'standard paradigm', holds that the permanent loss of the functions of the entire brain marks the end of the integrative unity of the body. In my response to Shewmon's article, I first offer a brief summary of the standard paradigm and cite recent work by advocates of whole brain criteria who tenaciously cling to the standard paradigm despite increasing evidence showing that it has significant weaknesses. Second, I address Shewmon's case against the standard paradigm, arguing that he is successful in showing that whole brain dead patients have integrated organic unity. Finally, I discuss some minor problems with Shewmon's article, along with suggestions for further elaboration.

  9. On the fate of laser-produced NH 2 in a constrained pulsed expansion of trimethylamine alane and NH 3

    NASA Astrophysics Data System (ADS)

    Demchuk, Alexander; Cahill, John J.; Simpson, Steven; Koplitz, Brent

    2001-11-01

    The effects of both 193 nm radiation and NH 3 on an expansion of trimethylamine alane (TMAA) have been studied. In neat TMAA, 193 nm radiation induces small but significant clustering. When NH 3 is introduced in the absence of 193 nm photons, no visible reaction occurs. However, when NH 3 is introduced along with 193 nm photons, the H 3Al:N(CH 3) 3 parent molecule is completely replaced by H 3AlNH 2. Moreover, the clustering channels observed with neat TMAA disappear. The apparent stability or inertness of the R 3MNH 2 (R=H, CH 3 or C 2H 5; M=Ga or Al) species in a variety of metal nitride reactive environments is discussed.

  10. Epitaxial Growth of Aluminum on Silicon Substrates by Metalorganic Molecular Beam Epitaxy using Dimethyl-Ethylamine Alane

    NASA Astrophysics Data System (ADS)

    Neo, Yoichiro; Otoda, Toshihiro; Sagae, Katumi; Mimura, Hidenori; Yokoo, Kuniyoshi

    1998-05-01

    In this paper, the growth process of aluminum on a silicon substrate by metalorganic molecular beam epitaxy using dimethyl-ethylamine alane has been described. The crystallographic orientation of the aluminum grains strongly depends on the substrate temperature. The epitaxial single crystalline (111) Al grains grow on a (111) Si substrate at a substrate temperature between 450 and 500°C. The bi-crystalline (110) Al grains grow on a (100) Si substrate at the substrate temperature between 350 and 450°C. For a (100) Si substrate, the orientation of Al is related to the reconstruction of the Si substrate. Furthermore, the selective growth of Al into 1.5-µm-diameter via-holes is shown to be possible.

  11. A Comparison between AlN Films Grown by MOCVD Using Dimethylethylamine Alane and Trimethylaluminium as the Aluminium Precursors

    NASA Astrophysics Data System (ADS)

    Hu, Wei-Guo; Liu, Xiang-Lin; Zhang, Pan-Feng; Zhao, Feng-Ai; Jiao, Chun-Mei; Wei, Hong-Yuan; Zhang, Ri-Qing; Wu, Jie-Jun; Cong, Guang-Wei; Pan, Yi

    2007-02-01

    Aluminium nitride (AlN) films grown with dimethylethylamine alane (DMEAA) are compared with the ones grown with trimethylaluminium (TMA). In the high-resolution x-ray diffraction Ω scans, the full width at half maximum (FWHM) of (0002) AlN films grown with DMEAA is about 0.70 deg, while the FWHM of (0002) AlN films grown with TMA is only 0.11 deg. The surface morphologies of the films are different, and the rms roughnesses of the surface are approximately identical. The rms roughness of AlN films grown with DMEAA is 47.4 nm, and grown with TMA is 69.4 nm. Although using DMEAA as the aluminium precursor cannot improve the AlN crystal quality, AlN growth can be reached at low temperature of 673 K. Thus, DMEAA is an alternative aluminium precursor to deposit AlN film at low growth temperatures.

  12. D. Alan Shewmon and the PCBE's White Paper on Brain Death: are brain-dead patients dead?

    PubMed

    Brugger, E Christian

    2013-04-01

    The December 2008 White Paper (WP) on "Brain Death" published by the President's Council on Bioethics (PCBE) reaffirmed its support for the traditional neurological criteria for human death. It spends considerable time explaining and critiquing what it takes to be the most challenging recent argument opposing the neurological criteria formulated by D. Alan Shewmon, a leading critic of the "whole brain death" standard. The purpose of this essay is to evaluate and critique the PCBE's argument. The essay begins with a brief background on the history of the neurological criteria in the United States and on the preparation of the 2008 WP. After introducing the WP's contents, the essay sets forth Shewmon's challenge to the traditional neurological criteria and the PCBE's reply to Shewmon. The essay concludes by critiquing the WP's novel justification for reaffirming the traditional conclusion, a justification the essay finds wanting.

  13. Revisiting the ALA/N (alpha-lipoic acid/low-dose naltrexone) protocol for people with metastatic and nonmetastatic pancreatic cancer: a report of 3 new cases.

    PubMed

    Berkson, Burton M; Rubin, Daniel M; Berkson, Arthur J

    2009-12-01

    The authors, in a previous article, described the long-term survival of a man with pancreatic cancer and metastases to the liver, treated with intravenous alpha-lipoic acid and oral low-dose naltrexone (ALA/N) without any adverse effects. He is alive and well 78 months after initial presentation. Three additional pancreatic cancer case studies are presented in this article. At the time of this writing, the first patient, GB, is alive and well 39 months after presenting with adenocarcinoma of the pancreas with metastases to the liver. The second patient, JK, who presented to the clinic with the same diagnosis was treated with the ALA/N protocol and after 5 months of therapy, PET scan demonstrated no evidence of disease. The third patient, RC, in addition to his pancreatic cancer with liver and retroperitoneal metastases, has a history of B-cell lymphoma and prostate adenocarcinoma. After 4 months of the ALA/N protocol his PET scan demonstrated no signs of cancer. In this article, the authors discuss the poly activity of ALA: as an agent that reduces oxidative stress, its ability to stabilize NF(k)B, its ability to stimulate pro-oxidant apoptosic activity, and its discriminative ability to discourage the proliferation of malignant cells. In addition, the ability of lowdose naltrexone to modulate an endogenous immune response is discussed. This is the second article published on the ALA/N protocol and the authors believe the protocol warrants clinical trial.

  14. The reactivity of sodium alanates with O[2], H[2]O, and CO[2] : an investigation of complex metal hydride contamination in the context of automotive systems.

    SciTech Connect

    Dedrick, Daniel E.; Bradshaw, Robert W.; Behrens, Richard, Jr.

    2007-08-01

    Safe and efficient hydrogen storage is a significant challenge inhibiting the use of hydrogen as a primary energy carrier. Although energy storage performance properties are critical to the success of solid-state hydrogen storage systems, operator and user safety is of highest importance when designing and implementing consumer products. As researchers are now integrating high energy density solid materials into hydrogen storage systems, quantification of the hazards associated with the operation and handling of these materials becomes imperative. The experimental effort presented in this paper focuses on identifying the hazards associated with producing, storing, and handling sodium alanates, and thus allowing for the development and implementation of hazard mitigation procedures. The chemical changes of sodium alanates associated with exposure to oxygen and water vapor have been characterized by thermal decomposition analysis using simultaneous thermogravimetric modulated beam mass spectrometry (STMBMS) and X-ray diffraction methods. Partial oxidation of sodium alanates, an alkali metal complex hydride, results in destabilization of the remaining hydrogen-containing material. At temperatures below 70 C, reaction of sodium alanate with water generates potentially combustible mixtures of H{sub 2} and O{sub 2}. In addition to identifying the reaction hazards associated with the oxidation of alkali-metal containing complex hydrides, potential treatment methods are identified that chemically stabilize the oxidized material and reduce the hazard associated with handling the contaminated metal hydrides.

  15. Proton-transfer and H2-elimination reactions of trimethylamine alane: role of dihydrogen bonding and Lewis acid-base interactions.

    PubMed

    Filippov, Oleg A; Tsupreva, Victoria N; Golubinskaya, Lyudmila M; Krylova, Antonina I; Bregadze, Vladimir I; Lledos, Agusti; Epstein, Lina M; Shubina, Elena S

    2009-04-20

    Proton-transfer and H(2)-elimination reactions of aluminum hydride AlH(3)(NMe(3)) (TMAA) with XH acids were studied by means of IR and NMR spectroscopy and DFT calculations. The dihydrogen-bonded (DHB) intermediates in the interaction of the TMAA with XH acids (CH(3)OH, (i)PrOH, CF(3)CH(2)OH, adamantyl acetylene, indole, 2,3,4,5,6-pentafluoroaniline, and 2,3,5,6-tetrachloroaniline) were examined experimentally at low temperatures, and the spectroscopic characteristics, dihydrogen bond strength and structures, and the electronic and energetic characteristics of these complexes were determined by combining experimental and theoretical approaches. The possibility of two different types of DHB complexes with polydentate proton donors (typical monodentate and bidentate coordination with the formation of a symmetrical chelate structure) was shown by DFT calculations and was experimentally proven in solution. The DHB complexes are intermediates of proton-transfer and H(2)-elimination reactions. The extent of this reaction is very dependent on the acid strength and temperature. With temperature increases the elimination of H(2) was observed for OH and NH acids, yielding the reaction products with Al-O and Al-N bonds. The reaction mechanism was computationally studied. Besides the DHB pathway for proton transfer, another pathway starting from a Lewis complex was discovered. Preference for one of the pathways is related to the acid strength and the nucleophilicity of the proton donor. As a consequence of the dual Lewis acid-base nature of neutral aluminum hydride, participation of a second ROH molecule acting as a bifunctional catalyst forming a six-member cycle connecting aluminum and hydride sites notably reduces the reaction barrier. This mechanism could operate for proton transfer from weak OH acids to TMAA in the presence of an excess of proton donor.

  16. Apollo 12 Mission image - Astronaut Alan L. Bean,lunar module pilot,and two U.S. spacecraft

    NASA Image and Video Library

    1969-11-20

    AS12-48-7136 (20 Nov. 1969) --- Astronaut Charles Conrad Jr., commander, examines the unmanned Surveyor 3 spacecraft during the second Apollo 12 extravehicular activity (EVA). In the background is the lunar module, parked where the crew had landed it in the Ocean of Storms only 600 feet from Surveyor 3. This series of pictures documents the only occasion wherein Apollo astronauts landed near or had hands-on contact with another spacecraft which had arrived on the moon's surface well ahead of them. This picture was taken by astronaut Alan L. Bean, lunar module pilot. The television camera and several other pieces were taken from Surveyor 3 and brought back to Earth for scientific examination. Surveyor 3 soft-landed on the moon on April 19, 1967. Astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) in lunar orbit while astronauts Conrad and Bean descended in the LM to explore the moon. Photo credit: NASA

  17. Towards understanding a mechanism for reversible hydrogen storage: theoretical study of transition metal catalysed dehydrogenation of sodium alanate.

    PubMed

    Ljubić, Ivan; Clary, David C

    2010-04-28

    On the basis of density functional theory and coupled-cluster CCSD(T) calculations we propose a mechanism of the dehydrogenation of transition metal doped sodium alanate. Insertion of two early 3d-transition metals, scandium and titanium, both of which are promising catalysts for reversible hydrogen storage in light metal hydrides, is compared. The mechanism is deduced from studies on the decomposition of a model system consisting of one transition metal atom and two NaAlH(4) units. Subsequently, the significance of such minimal cluster model systems to the real materials is tested by embedding the systems into the surface of the NaAlH(4) crystal. It is found that the dehydrogenation proceeds via breaking of the bridge H-Al bond and consequent formation of intermediate coordination compounds in which the H(2) molecule is side-on (eta(2)-) bonded to the transition metal centre. The total barrier to the H(2) release is thus dependent upon both the strength of the Al-H bond to be broken and the depth of the coordinative potential. The analogous mechanism applies for the recognized three successive dehydrogenation steps. The gas-phase model structures embedded into the surface of the NaAlH(4) crystal exhibit an unambiguous kinetic stability and their general geometric features remain largely unchanged.

  18. Trimethylamine alane for low-pressure MOVPE growth of AlGaAs-based materials and device structures

    SciTech Connect

    Schneider, R.P.; Bryan, R.P.; Jones, E.D.; Biefield, R.M.; Olbright, G.R.

    1991-12-31

    The use of trimethylamine alane (TMAA1) as an alternative to trimethylaluminum (TMA1) for low-pressure metalorganic vapor-phase epitaxy (MOVPE) of AlGaAs thin films as well as complex optoelectronic device structures has been studied in detail. AlGaAs layers were grown in a horizontal reaction chamber at 20--110 mbar with growth temperatures in the range 650{degrees}C {le} T{sub G} {le} 750{degrees}C. Wafer thickness uniformity is strongly dependent on growth pressure, and is acceptable only for the highest linear flow velocities. The 12K photoluminescence (PL) spectra of AlGaAs layers grown using TMAA1 and TEGa exhibit uniformly intense and narrow bound-exciton emission throughout the growth temperature range investigated. To assess the viability of this new source for the low-pressure OMVPE growth of advanced optoelectronic devices, several optically-pumped vertical-cavity surface-emitting laser (VCSEL) structures were grown using TMAA1 extensively. Room temperature lasing at 850 nm was reproducibly obtained from the VCSEL structures, with a threshold pumping power comparable to similar structures grown by molecular beam epitaxy in our laboratories.

  19. Synthesis and platinum complexes of an alane-appended 1,1'-bis(phosphino)ferrocene ligand.

    PubMed

    Cowie, Bradley E; Tsao, Fu An; Emslie, David J H

    2015-02-09

    An aryldimethylalane-appended analogue of 1,1'-bis(diphenylphosphino)ferrocene, FcPPAl, was prepared, and reaction with [Pt(nb)3 ] (nb=norbornene) afforded [Pt(η(2) -nb)(FcPPAl)] (1). Heating a solution of 1 to 80 °C resulted in crystallization of [{Pt(FcPPAl)}2 ] (2), whereas treatment of 1 with C2 H4 , C2 Ph2 , H2 , or CO provided [PtL(FcPPAl)] [L=C2 H4 (3), C2 Ph2 (4)], [PtH2 (FcPPAl)] (5), and [Pt(CO)(FcPPAl)] (6). In all complexes, the FcPPAl ligand is coordinated through both phosphines and the alane. Whereas 2 adopts a T-shaped geometry at platinum, 3-5 are square-pyramidal, and 6 is distorted square-planar. The hydride and carbonyl complexes feature unusual multicenter bonding involving platinum, aluminum, and a hydride or carbonyl ligand. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Metalorganic chemical vapor deposition growth of high-quality AlGaAs using dimethylethylamine alane and triethylgallium dimethylethylamine adduct

    NASA Astrophysics Data System (ADS)

    Miyashita, M.; Kizuki, H.; Tsugami, M.; Fujii, N.; Mihashi, Y.; Takamiya, S.

    1998-08-01

    High-purity Al 0.25Ga 0.75As layer has been successfully obtained by metalorganic chemical vapor deposition (MOCVD) using new precursors of dimethylethylamine alane (DMEAA) and triethylgallium-dimethylethylamine adduct (TEG-DMEA). It is shown that the concentrations of residual carbon and oxygen in the AlGaAs layer grown at a relatively low V/III ratio were under detection limits of secondary-ion mass spectrometry (3.0×10 15 and 5.0×10 15 cm -3, respectively). In the photoluminescence spectra at 4.2 K, the peak intensity of carbon-related emission was much weaker than that of bound-exciton (BE) emission. The full-width at half-maximum for the BE peak was as narrow as 5.6 meV. Any predeposition between these precursors due to a gas-phase prereaction was not observed. These results indicate that the combination of DMEAA and TEG-DMEA are promising precursors for MOCVD growth of AlGaAs with low residual impurity concentration.

  1. Trimethylamine alane for low-pressure MOVPE growth of AlGaAs-based materials and device structures

    SciTech Connect

    Schneider, R.P.; Bryan, R.P.; Jones, E.D.; Biefield, R.M. ); Olbright, G.R. )

    1991-01-01

    The use of trimethylamine alane (TMAA1) as an alternative to trimethylaluminum (TMA1) for low-pressure metalorganic vapor-phase epitaxy (MOVPE) of AlGaAs thin films as well as complex optoelectronic device structures has been studied in detail. AlGaAs layers were grown in a horizontal reaction chamber at 20--110 mbar with growth temperatures in the range 650{degrees}C {le} T{sub G} {le} 750{degrees}C. Wafer thickness uniformity is strongly dependent on growth pressure, and is acceptable only for the highest linear flow velocities. The 12K photoluminescence (PL) spectra of AlGaAs layers grown using TMAA1 and TEGa exhibit uniformly intense and narrow bound-exciton emission throughout the growth temperature range investigated. To assess the viability of this new source for the low-pressure OMVPE growth of advanced optoelectronic devices, several optically-pumped vertical-cavity surface-emitting laser (VCSEL) structures were grown using TMAA1 extensively. Room temperature lasing at 850 nm was reproducibly obtained from the VCSEL structures, with a threshold pumping power comparable to similar structures grown by molecular beam epitaxy in our laboratories.

  2. Strong dissimilarities between the gas-phase acidities of saturated and alpha,beta-unsaturated boranes and the corresponding alanes and gallanes.

    PubMed

    Gámez, José A; Guillemin, Jean-Claude; Mó, Otilia; Yáñez, Manuel

    2008-01-01

    The effect that unsaturation has on the intrinsic acidity of boranes, alanes, and gallanes, was analyzed by B3 LYP and CCSD(T)/6-311+G(3df,2p) calculations on methyl-, ethyl-, vinyl-, and ethynylboranes, -alanes and -gallanes, and on the corresponding hydrides XH3. Quite unexpectedly, methylborane, which behaves as a carbon acid, is predicted to have an intrinsic acidity almost 200 kJ mol(-1) stronger than BH3, reflecting the large reinforcement of the C--B bond, which upon deprotonation becomes a double bond through the donation of the lone pair created on the carbon atom into the empty p orbital of the boron. Also unexpectedly, and for the same reason, the saturated and alpha,beta-unsaturated boranes are much stronger acids than the corresponding hydrocarbons, in spite of being carbon acids as well. The Al derivatives also behave as carbon acids, but in this case the most favorable deprotonation process occurs at C beta, leading to the formation of rather stable three-membered rings, again through the donation of the C beta lone pair into the empty p orbital of Al. For Ga-containing compounds the deprotonation of the GaH2 group is the most favorable process. Therefore only Ga derivatives behave similarly to the analogues of Groups 14, 15, and 16 of the periodic table, and the saturated derivatives exhibit a weaker acidity than the unsaturated ones. Within Group 13, boranes are stronger acids than alanes and gallanes. For ethyl and vinyl derivatives, alanes are stronger acids than gallanes. We have shown, for the first time, that acidity enhancement for primary heterocompounds is not only dictated by the position of the heteroatom in the periodic table and the nature of the substituent, but also by the bonding rearrangements triggered by the deprotonation of the neutral acid.

  3. Silver Nanoparticles

    NASA Astrophysics Data System (ADS)

    Khaydarov, R. R.; Khaydarov, R. A.; Estrin, Y.; Evgrafova, S.; Scheper, T.; Endres, C.; Cho, S. Y.

    The bactericidal effect of silver nanoparticles obtained by a novel electrochemical method on Escherichia coli, Staphylococcus aureus, Aspergillus niger and Penicillium phoeniceum cultures has been studied. The tests conducted have demonstrated that synthesized silver nanoparticles — when added to water paints or cotton fabrics — show a pronounced antibacterial/antifungal effect. It was shown that smaller silver nanoparticles have a greater antibacterial/antifungal efficacy. The paper also provides a review of scientific literature with regard to recent developments in the field of toxicity of silver nanoparticles and its effect on environment and human health.

  4. Intermetallic nanoparticles

    DOEpatents

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules

    2015-07-14

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  5. Intermetallic nanoparticles

    DOEpatents

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules L.

    2017-01-03

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  6. Intermetallic nanoparticles

    SciTech Connect

    Singh, Dileep; Yusufoglu, Yusuf; Timofeeva, Elena; Routbort, Jules L.

    2015-11-20

    A process for preparing intermetallic nanoparticles of two or more metals is provided. In particular, the process includes the steps: a) dispersing nanoparticles of a first metal in a solvent to prepare a first metal solution, b) forming a reaction mixture with the first metal solution and a reducing agent, c) heating the reaction mixture to a reaction temperature; and d) adding a second metal solution containing a salt of a second metal to the reaction mixture. During this process, intermetallic nanoparticles, which contain a compound with the first and second metals are formed. The intermetallic nanoparticles with uniform size and a narrow size distribution is also provided. An electrochemical device such as a battery with the intermetallic nanoparticles is also provided.

  7. Historical streamflows of Double Mountain Fork of Brazos River and water-surface elevations of Lake Alan Henry, Garza County, Texas, water years 1962-2010

    USGS Publications Warehouse

    Asquith, William H.; Vrabel, Joseph

    2011-01-01

    The U.S. Geological Survey (USGS), in cooperation with the City of Lubbock, Texas, operates two surface-water stations in Garza County, Tex.: USGS streamflow-gaging station 08079600 Double Mountain Fork Brazos River at Justiceburg, Tex., and 08079700 Lake Alan Henry Reservoir, a water-supply reservoir about 60 miles southeast of Lubbock, Tex., and about 10 miles east of Justiceburg, Tex. The streamflow and water-surface elevation data from the two stations are useful to water-resource managers and planners in support of forecasting and water-resource infrastructure operations and are used in regional hydrologic studies.

  8. Studying aluminum hydride by means of thermal analysis

    NASA Astrophysics Data System (ADS)

    Milekhin, Yu. M.; Koptelov, A. A.; Matveev, A. A.; Baranets, Yu. N.; Bakulin, D. A.

    2015-07-01

    Chemical reactions and physical transformations that occur upon heating aluminum hydride (AlH3, alane), stored for 25 years, in the temperature range of 50-1200°C in an atmosphere of nitrogen, argon, and air are studied by means of thermogravimetric analysis and differential scanning calorimetry. The heat of thermal decomposition and the hydrogen content are determined for the AlH3 samples and are found to be 318 ± 25 J/g and 9.32 ± 0.24 wt %, respectively. It is established that the estimated enthalpy of formation of AlH3 in stoichiometric composition (Δf H ≈ -10.3 kJ/mol) agrees with the literature data. After the release of hydrogen, the mass of the precipitate increases by 0.5 ± 0.3%, relative to the initial mass of the AlH3 samples; the most likely reason for this effect is the adsorption of nitrogen (argon) in the micropores and mesopores that form. Thermal phenomena associated with the crystallization of the amorphous aluminum that forms after hydrogen is released from the alane particles are analyzed. It is established that the aluminum contained in initial AlH3 samples is almost completely transformed into aluminum nitride and oxide (AlN and Al3O3) upon heating to 1200°C in nitrogen and air, respectively.

  9. Precision Nanoparticles

    ScienceCinema

    John Hemminger

    2016-07-12

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  10. Polymeric nanoparticles

    PubMed Central

    Bolhassani, Azam; Javanzad, Shabnam; Saleh, Tayebeh; Hashemi, Mehrdad; Aghasadeghi, Mohammad Reza; Sadat, Seyed Mehdi

    2014-01-01

    Nanocarriers with various compositions and biological properties have been extensively applied for in vitro/in vivo drug and gene delivery. The family of nanocarriers includes polymeric nanoparticles, lipid-based carriers (liposomes/micelles), dendrimers, carbon nanotubes, and gold nanoparticles (nanoshells/nanocages). Among different delivery systems, polymeric carriers have several properties such as: easy to synthesize, inexpensive, biocompatible, biodegradable, non-immunogenic, non-toxic, and water soluble. In addition, cationic polymers seem to produce more stable complexes led to a more protection during cellular trafficking than cationic lipids. Nanoparticles often show significant adjuvant effects in vaccine delivery since they may be easily taken up by antigen presenting cells (APCs). Natural polymers such as polysaccharides and synthetic polymers have demonstrated great potential to form vaccine nanoparticles. The development of new adjuvants or delivery systems for DNA and protein immunization is an expanding research field. This review describes polymeric carriers especially PLGA, chitosan, and PEI as vaccine delivery systems. PMID:24128651

  11. Precision Nanoparticles

    SciTech Connect

    John Hemminger

    2009-07-21

    A revolutionary technology that efficiently produces nanoparticles in uniform and prescribed sizes (1-100 nanometers) using supercritical fluids. INL researcher Robert Fox was joined by Idaho State University researchers Rene Rodriquez and Joshua Pak in d

  12. Optimisation des transferts de chaleur dans un systeme de stockage d'hydrogene a base d'alanate de sodium

    NASA Astrophysics Data System (ADS)

    Bhouri, Maha

    Le déploiement des applications de transport basées sur l'hydrogène comme source d'énergie est assujetti à l'identification d'une méthode efficace pour son stockage. En ce qui concerne la voie de stockage solide, les principaux inconvénients sont les faibles propriétés thermiques de l'hydrure, le long temps de chargement du réservoir et sa faible capacité gravimétrique. Dans ce cadre, l'alanate de sodium est choisi comme matériau de référence pour optimiser le fonctionnement d'un système de stockage d'un kilogramme d'hydrogène, en termes d'efficacité thermique et de capacités gravimétrique et volumétrique. Trois configurations ont été considérées en variant la disposition du lit d'hydrure et du fluide de refroidissement ainsi que le choix des échangeurs de chaleur et des structures permettant l'amélioration des propriétés thermiques de ce lit. Le modèle mathématique décrivant les transferts de chaleur et de masse au sein du lit d'hydrure a été résolu avec le logiciel commercial COMSOL Multiphysics® 3.5a. Les résultats numériques nous ont permis de déterminer l'interaction entre les propriétés géométriques des éléments d'échange de chaleur et le taux de stockage d'hydrogène ainsi que sa dépendance des conditions opérationnelles. L'efficacité thermique du système de stockage est déterminée en comparant le taux de stockage d'hydrogène calculé à celui issu du modèle de cinétique et validé avec les données expérimentales. Une fois que la quantité d'hydrogène stocké est optimisée, la contribution des éléments d'échange de chaleur au poids et au volume du réservoir et les capacités gravimétrique et volumétrique des configurations correspondantes sont déterminées et discutées en fonction des critères de sélection fixées par le DOE.

  13. Finite size effect on hydrogen bond cooperativity in (Ala)n polypeptides: A DFT study using numeric atom-centered orbitals

    NASA Astrophysics Data System (ADS)

    Blum, Volker; Ireta, Joel; Scheffler, Matthias

    2007-03-01

    An accurate representation of the energetic contribution Ehb of hydrogen bonds to structure formation is paramount to understand the secondary structure stability of proteins, both qualitatively and quantitatively. However, Ehb depends strongly on its environment, and even on the surrounding peptide conformation itself. For instance, a short α-helical polypeptide (Ala)4 can not be stabilized by its single hydrogen bond, whereas an infinite α-helical chain (Ala)∞ is clearly energetically stable over a fully extended conformation. We here use all-electron density functional calculations in the PBE generalized gradient approximation by a recently developed, computationally efficient numeric atom-centered orbital based code^1 to investigate this H-bond cooperativity that is intrinsic to Alanine-based polypeptides (Ala)n (n=1-20,∞). We compare finite and infinite prototypical helical conformations (α, π, 310) on equal footing, with both neutral and ionic termination for finite (Ala)n peptides. Moderately sized NAO basis sets allow to capture Ehb with meV accuracy, revealing a clear jump in Ehb (cooperativity) when two H-bonds first appear in line, followed by slower and more continuous increase of Ehb towards n->∞. ^1 V. Blum, R. Gehrke, P. Havu, V. Havu, M. Scheffler, The FHI Ab Initio Molecular Simulations (aims) Project, Fritz-Haber-Institut, Berlin (2006).

  14. Intra- and intermolecular N-H...F-C hydrogen-bonding interactions in amine adducts of tris(pentafluorophenyl)borane and -alane.

    PubMed

    Mountford, Andrew J; Lancaster, Simon J; Coles, Simon J; Horton, Peter N; Hughes, David L; Hursthouse, Michael B; Light, Mark E

    2005-08-08

    The reaction between B(C(6)F(5))(3) and NH(3)(g) in light petroleum yielded the solvated adduct H(3)N.B(C(6)F(5))(3).NH(3). Treatment with a second equivalent of B(C(6)F(5))(3) afforded H(3)N.B(C(6)F(5))(3). Attempts to prepare the analogous alane adduct were unsuccessful and resulted in protolysis. Related compounds of the form R'R' 'N(H).M(C(6)F(5))(3) were synthesized from M(C(6)F(5))(3) and the corresponding primary and secondary amines (M = B, Al; R' = H, Me, CH(2)Ph; R' ' = Me, CH(2)Ph, CH(Me)(Ph); R'R' ' = cyclo-C(5)H(10)). The solid-state structures of 13 new compounds have been elucidated by single-crystal X-ray diffraction and are discussed. Each of the borane adducts has a significant bifurcated intramolecular hydrogen bond between an amino hydrogen and two o-fluorines, while N-H...F-C interactions in the alane adducts are weaker and more variable. (19)F NMR studies demonstrate that the borane adducts retain the bifurcated C-F...H...F-C hydrogen bond in solution. Compounds of the type R'R' 'N(H).M(C(6)F(5))(3) conform to Etter's rules for the prediction of hydrogen-bonding interactions.

  15. Nanoparticle vaccines.

    PubMed

    Zhao, Liang; Seth, Arjun; Wibowo, Nani; Zhao, Chun-Xia; Mitter, Neena; Yu, Chengzhong; Middelberg, Anton P J

    2014-01-09

    Nanotechnology increasingly plays a significant role in vaccine development. As vaccine development orientates toward less immunogenic "minimalist" compositions, formulations that boost antigen effectiveness are increasingly needed. The use of nanoparticles in vaccine formulations allows not only improved antigen stability and immunogenicity, but also targeted delivery and slow release. A number of nanoparticle vaccines varying in composition, size, shape, and surface properties have been approved for human use and the number of candidates is increasing. However, challenges remain due to a lack of fundamental understanding regarding the in vivo behavior of nanoparticles, which can operate as either a delivery system to enhance antigen processing and/or as an immunostimulant adjuvant to activate or enhance immunity. This review provides a broad overview of recent advances in prophylactic nanovaccinology. Types of nanoparticles used are outlined and their interaction with immune cells and the biosystem are discussed. Increased knowledge and fundamental understanding of nanoparticle mechanism of action in both immunostimulatory and delivery modes, and better understanding of in vivo biodistribution and fate, are urgently required, and will accelerate the rational design of nanoparticle-containing vaccines. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Nanoparticle standards

    SciTech Connect

    Havrilla, George Joseph

    2016-12-08

    We will purchase a COTS materials printer and adapt it for solution printing of known elemental concentration solutions. A methodology will be developed to create deposits of known mass in known locations on selected substrates. The deposits will be characterized for deposited mass, physical morphology, thickness and uniformity. Once an acceptable methodology has been developed and validated, we will create round robin samples to be characterized by LGSIMS instruments at LANL, PNNL and NIST. We will demonstrate the feasibility of depositing nanoparticles in known masses with the goal of creating separated nanoparticles in known locations.

  17. Al2O3 thin films by plasma-enhanced chemical vapour deposition using trimethyl-amine alane (TMAA) as the Al precursor

    NASA Astrophysics Data System (ADS)

    Chryssou, C. E.; Pitt, C. W.

    We report the low temperature (200-300 °C) deposition of uniform, amorphous Al2O3 thin films by plasma-enhanced chemical vapour deposition (PECVD) using trimethyl-amine alane (TMAA) as the Al precursor. The thin films were deposited on both Si and quartz silica (SiO2) substrates. Deposition rates were typically 60 Åmin-1 keeping the TMAA temperature constant at 45 °C. The deposited Al2O3 thin films were stoichiometric alumina with low carbon contamination (0.7-1.3 At%). The refractive index ranged from 1.54 to 1.62 depending on the deposition conditions. The deposition rate was studied as a function of both the RF power and the substrate temperature. The structure and the surface of the deposited Al2O3 thin films were studied using X-ray diffraction, atomic force microscopy (AFM) and scanning electron microscopy (SEM).

  18. Reaction of Dimethylethylamine Alane and Ammonia on Si(100) during the Atomic Layer Growth of AIN: Static SIMS, TPSIMS, and TPD

    SciTech Connect

    Rogers, JW Bill W. )

    2000-01-01

    Dimethylethylamine alane (DMEAA; AIH3: N(CH3)2(CH2CH3)) has been used as an Al source in the chemical vapor deposition of AIN. In the Atomic Layer Growth (ALG) mode, ammonia and DMEAA interact selectively by nucleophilic displacement. In the first part of this study, the surface adsorption and reaction processes are characterized with static secondary-ion mass spectrometry (SIMS) and temperature-programmed secondary-ion mass spectrometry (TPSIMS). The secondary ion emission from DMEAA-covered Si surface shares similar general characteristics with the gas phase cracking pattern. The secondary ion emission spectrum is interpreted according to a unimolecular ion decomposition mechanism and is used as the fingerprint for the presence of molecular DMEAA. During the surface reaction between DMEAA and ammonia, the intensity of the fingerprint peaks diminishes, representing the departure of the amine ligand. The thermal stability of DMEAA and its decomposition behavior on Si are also examined.

  19. Atomic layer epitaxy of AlP and (AlP) n(GaP) n superlattice using ethyldimethylamine alane as a new aluminum source

    NASA Astrophysics Data System (ADS)

    Hirose, Shingo; Yamaura, Masaaki; Munekata, Hiro

    1999-08-01

    Atomic layer epitaxy (ALE) of AlP was realized using ethyldimethylamine alane (EDMAAl) as a new Al source. Self-limiting growth of AlP took place at one and two monolayers per ALE cycle. Secondary ion mass spectroscopy revealed that the amounts of incorporated impurities (carbon, hydrogen and oxygen) in ALE-grown AlP layers was greatly suppressed by using the new Al source, to nearly the same levels as in high-quality MOVPE-grown layers. We also achieved the successful ALE growth of (AlP) n(GaP) n short-period superlattices (SLs), taking advantage of the overlapping temperature windows of ALE-GaP and ALE-AlP. X-ray diffraction measurements showed reasonably good interface abruptness of SLs as low as 3. The PL emission peak from SLs involving Al-containing layers was observed in ALE growth for the first time.

  20. Robust Nanoparticles

    DTIC Science & Technology

    2015-01-21

    advanced the chemis1:Iy of ftmctional nanopruiicles and used these patiicles in advanced materials assembly for the fabrication of nanopatiicle...polymer ligands, and the robustness resulting fi:om ligand cross-linking post- assembly . The project developed a facile evaporative assembly method...used these particles in advanced materials assembly for the fabrication of nanoparticle-based mesostructures. These hybrid materials possess extremely

  1. Chemical vapor deposition of palladium thin films from Lewis base adducts of Pd(hfac)(2) and of aluminum thin films from diethylamido alanes

    NASA Astrophysics Data System (ADS)

    Bailey, Alec

    1999-11-01

    (N-Me-morpholine) (6) in an AACVD reactor. Deposition was found to be feed-rate limited for (3), ( 4), and (6). (5) Diethylamidoalane (8), bis(diethylamido)alane (9) and diisopropylamidoalane ( 10) were synthesized, characterized and investigated as CVD precursors for the deposition of aluminum thin films. All three alanes were characterized by 1H, 13C{1H} 14N, and 27Al NMR spectroscopy and structurally characterized in the solid-state by single-crystal X-ray diffraction methods. Chemical vapor deposition of aluminum thin films was performed with diethylamidoalane and bis(diethylamido)alane on silicon(111) substrates in a HVCVD reactor.

  2. Helical secondary structure of polyalanine peptides in vacuo: Ac-Alan-LysH^+ (n=5,10,15), experiment and theory

    NASA Astrophysics Data System (ADS)

    Rossi, Mariana; Blum, Volker; Kupser, Peter; von Helden, Gert; Bierau, Frauke; Meijer, Gerard; Scheffler, Matthias

    2009-03-01

    The presence of a solvent is often viewed as indispensable to explain the structure of peptides and proteins. However, well defined secondary structure motifs (helices, sheets, ...) also exist in vacuo, offering a unique ``clean room'' condition to quantify the stabilizing interactions. We here unravel the structure of LysineH^+ capped polyalanine peptides Ac-Alan-LysH^+ (n-5,10,15), by combining experimental multi-photon IR spectra obtained using the FELIX free-electron laser at room-temperature with van der Waals-corrected all-electron density-functional theory (DFT) in the generalized gradient approximation in the FHI-aims code [1]. Earlier ion mobility studies of these molecules indicate helical structure [2], which we here demonstrate quantitatively. For n=5, we find a close energetic competition of different helix motifs (α, 310), with similar and good agreement between measured and calculated vibrational spectra. We show how the LysH^+ termination acts to induce helices also for longer peptides, and how vibrational modes develop with helix length (n=10,15), yielding, e.g., a softening of collective modes towards the infinite helix limit. [1] V. Blum et al, Comp. Phys. Comm. (2008), accepted. [2] M. Kohtani et al., JACS 120, 12975 (1998).

  3. Microstructure and properties of aluminum contacts formed on GaAs(100) by low pressure chemical vapor deposition with dimethylethylamine alane source

    NASA Astrophysics Data System (ADS)

    Shashkin, V.; Rushworth, S.; Danil'Tsev, V.; Murel, A.; Drozdov, Yu.; Gusev, S.; Khrykin, O.; Vostokov, N.

    2001-08-01

    We report on a low pressure chemical vapor deposition of metallic thin aluminum films on GaAs (001) with a dimethylethylamine alane (DMEAA) source and H2 as a carrier gas. The deposition temperatures varied in the range 130-360°C. Integrated volumes for Al (111), (100), (110)R, and (110) grains were estimated by the x-ray diffraction technique and the growth temperature values preferred for every type of grains were observed. The experimentally observed dominance of Al(110)R over Al(110), irrespective of the substrate miscut direction, supports the GaAs(100) inner anisotropy effect on the Al grain orientation. Electrical resistivity was 5 ·cm for the best Al films. The Schottky barrier heights were near a 0.7 eV level and the ideality factor n=1.1. Nonalloyed ohmic contacts were fabricated on an n-type GaAs epitaxial layer with an additional set of Si-layers near the Al/GaAs interface. Specific contact resistance, c=7 cm2, was measured. Best contacts were obtained at a deposition temperature lower than 250°C.

  4. Chemical Vapor Deposition of TiAlN film by Using Titanium Tetrachloride, Dimethylethylamine Alane and Ammonia Gas for ULSI Cu Diffusion Barrier Application

    NASA Astrophysics Data System (ADS)

    Shin, Young-Hoon; Shimogaki, Yukihiro

    2004-12-01

    We report on the deposition of Ti1-xAlxN films by chemical vapor deposition (CVD) system. Titanium tetrachloride (TiCl4), dimethylethylamine alane (DMEAA) and ammonia gas were used as sources. Chemical composition, microstructure and electrical resistivity were investigated at various deposition conditions by X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy and 4 point probe. Al content, x, in Ti1-xAlxN film was varied from 0.04 to 0.79 in our experimental conditions. As deposition temperature increased in the temperature range from 220°C to 410°C, Al content decreased. Also, Al content in Ti1-xAlxN films shows a linear relationship with the partial pressure of DMEAA. Up to x=0.15, glancing angle XRD peaks showed only B1 (NaCl) cubic structures but further increasing of Al content leads to amorphous structure. For Ti0.76Al0.24N film, Cu(50 nm)/Ti0.76Al0.24N(20 nm)/Si substrate stack was prepared to examine the barrier property against Cu diffusion. Cu diffused into Si substrate through the Ti0.76Al0.24N(20 nm) film from 700°C, 30 min vacuum annealing. This result is higher than that of CVD-TiN(50 nm) barrier which failed at 400°C.

  5. Feasibility study of the direct mechano-chemical synthesis of nanostructured magnesium tetrahydroaluminate (alanate) [Mg(AlH(4))(2)] complex hydride.

    PubMed

    Varin, R A; Chiu, Ch; Czujko, T; Wronski, Z

    2005-10-01

    The present work reports a feasibility study of the direct mechano-chemical synthesis by controlled reactive mechanical alloying (CRMA) in a magneto-ball mill of the nanostructured magnesium tetrahydroaluminate (magnesium alanate) Mg(AlH(4))(2) complex hydride. Three stoichiometric Mg-2Al mixtures, (a) elemental Mg and Al powders, (b) elemental Al powder and commercial AZ91 alloy (Mg-Al-Zn alloy) and (c) powder of as-cast Mg-2Al alloy, have been used. No successful synthesis of Mg(AlH(4))(2) has been achieved. The only nanocrystalline hydride formed up to 270 h of CRMA is beta-MgH(2), and it does not react with Al and H(2) to form Mg(AlH(4))(2). It has been found that there is strong competition between formation of Al(Mg) solid solution and the beta-MgH(2) hydride occurring to a various extent up to approximately 10 h of CRMA in all three Mg-2Al mixtures. It is hypothesized that the presence of Al(Mg) solid solution inhibits the reaction of beta-MgH(2), Al and H(2) to form Mg(AlH(4))(2). Furthermore, despite the fact that after prolonged milling the Al(Mg) solution eventually decomposes into secondary Al(s) (derived from solid solution), the latter retains its physico-chemical characteristics of the former solid solution which still inhibits the reaction to form Mg(AlH(4))(2). Experimental evidence from DSC measurements shows increasing ranges of the melting enthalpy with increasing amounts of Al(Mg) solid solution and consequently the secondary Al(s) for all the three Mg-2Al mixtures. This strongly supports the hypothesis about the different nature of Al(Mg) and the secondary Al(s) as compared to the primary elemental Al powder.

  6. Studies of gas phase reactions, nucleation and growth mechanisms of plasma promoted chemical vapor deposition of aluminum using dimethylethylamine alane as source percursor

    NASA Astrophysics Data System (ADS)

    Knorr, Andreas H.

    The work presented herein focuses on the use of plasma promoted chemical vapor deposition (PPCVD) of aluminum (Al) using dimethylethylamine alane (DMEAA) as source precursor to provide an integrated, low temperature alternative to currently employed Al deposition methods in ultra large sale integration ULSI multilevel metal wiring schemes. In this respect, key findings are reported and discussed from critical scientific and technical aspects of an research and development effort, which was successfully executed to identify a viable Al CVD deposition process. In this respect, advanced atomic scale analytical techniques were successfully employed to characterize the PPCVD deposition process at the molecular level, and document the dependence of film's structural and compositional properties on key process parameters. This led to the development and optimization of a PPCVD Al process for ULSI applications. In addition, gas phase quadrupole mass spectrometry (QMS) was employed to study the gas phase evolution during TCVD and PPCVD in order to gain a thorough understanding of the potential chemical and physical reactions that could occur in the gas phase and derive corresponding optimized reaction pathways for both CVD processes. Key reaction mechanisms involved in thermal and plasma promoted CVD as a function of processing parameters were investigated, including the role of hydrogen plasma in providing an efficient pathway to aluminum nucleation and growth. The resulting reaction mechanisms were then employed to identify the most likely precursor decomposition pathways and explore relevant implications for thermal and plasma promoted CVD Al. Furthermore, the nucleation and growth of Al in both TCVD and PPCVD were thoroughly characterized. Time evolution studies were carried out employing a variety of relevant liners and seed layers under selected surface chemical states. The surface morphology of the resulting films were analyzed by means of scanning probe microscopy

  7. The use of 1,2-epoxyhexane as a passivating agent for core-shell aluminum nanoparticles with very high active aluminum content

    NASA Astrophysics Data System (ADS)

    Jelliss, Paul A.; Buckner, Steven W.; Chung, Stephen W.; Patel, Ashish; Guliants, Elena A.; Bunker, Christopher E.

    2013-09-01

    Aluminum nanoparticles synthesized by titanium (IV) isopropoxide-initiated decomposition of alane have been passivated and capped using oligomerization of 1,2-epoxyhexane. Preliminary synthetic protocols with this capping agent, where the nanoparticle formation reaction and passivation processes were both conducted at ambient temperatures, had resulted in nanoparticles that were highly unstable and that either oxidized rapidly upon exposure to air or were pyrophoric. Use of 1,2-epoxydodecane, on the other hand, had produced stable nanoparticles that were successfully characterized and reported. A modification of the procedure whereby the epoxyhexane passivation process is carried out at 85 °C for 30 min, has afforded surprisingly stable aluminum nanoparticles. Powder X-ray analysis and transmission electron microscopy reveal nanoparticle diameters on the order of 30 nm with 19 nm crystalline aluminum cores. The passivation process yields an extraordinarily high active aluminum (Al0) content of 83%, with degradation of the core to 52% active aluminum after 9 days exposure in a dry air chamber. Differential scanning calorimetry coupled with thermogravimetric analysis reveals distinct cap combustion and metal ignition exotherms, though they are not as well-defined as those found with their epoxydodecane-capped congener. With the additional observation of a metal melting endotherm, it is suggested that while carrying out the passivation process at an elevated temperature affords a higher degree of kinetic stabilization of the aluminum core, the passivation shell is inhomogeneous, possibly as a result of the polydisperse nature of the oligomerized epoxyhexane.

  8. Nanoparticles for photothermal therapies.

    PubMed

    Jaque, D; Martínez Maestro, L; del Rosal, B; Haro-Gonzalez, P; Benayas, A; Plaza, J L; Martín Rodríguez, E; García Solé, J

    2014-08-21

    The current status of the use of nanoparticles for photothermal treatments is reviewed in detail. The different families of heating nanoparticles are described paying special attention to the physical mechanisms at the root of the light-to-heat conversion processes. The heating efficiencies and spectral working ranges are listed and compared. The most important results obtained in both in vivo and in vitro nanoparticle assisted photothermal treatments are summarized. The advantages and disadvantages of the different heating nanoparticles are discussed.

  9. Shape tunable plasmonic nanoparticles

    DOEpatents

    El-Sayed, Mostafa A.; El-Sayed, Ivan Homer

    2017-03-07

    Noble metal nanoparticles and methods of their use are provided. Certain aspects provided solid noble metal nanoparticles tuned to the near infrared. The disclosed nanoparticles can be used in molecular imaging, diagnosis, and treatment. Methods for imaging cells are also provided.

  10. Clickable molecularly imprinted nanoparticles.

    PubMed

    Xu, Changgang; Ye, Lei

    2011-06-07

    Terminal alkynyl and azide groups are introduced on the surface of molecularly imprinted core-shell nanoparticles using precipitation polymerization. These clickable groups enable simple nanoparticle conjugation and surface modification under mild reaction conditions, opening new opportunities for nanoparticle-based assays and chemical sensing.

  11. The ALAN Review. Winter, 1984.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.

    1984-01-01

    Intended for the junior high school or secondary school English teacher, the articles and features in this journal focus on young adult literatue and the adolescent audience. The first article, Zibby Oneal's "Writing for Adolescents: Pleasures and Problems," describes the responsibilities of authors of adolescent fiction, while the second article,…

  12. The ALAN Review. Winter 1986.

    ERIC Educational Resources Information Center

    Reed, Arthea, Ed.

    1986-01-01

    Intended for junior or senior high school English teachers, articles and features in this journal issue focus on young adult literature and the adolescent audience. The first article, Kevin Major's "The Truth about My Fictitious Friends," describes the genesis of the author's fiction writing for the Newfoundland audience, and is followed…

  13. The ALAN Review. Winter, 1982.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1982-01-01

    Articles in this issue focus on adolescent literature. The first article is a reflection by author Katie Letcher Lyle on her personal experiences since the publication of her last novel. The second article examines the dramatic power of the novels of Alice Childress. The third article reports the results of a questionnaire on the reading…

  14. The ALAN Review. Winter, 1984.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.

    1984-01-01

    Intended for the junior high school or secondary school English teacher, the articles and features in this journal focus on young adult literatue and the adolescent audience. The first article, Zibby Oneal's "Writing for Adolescents: Pleasures and Problems," describes the responsibilities of authors of adolescent fiction, while the second article,…

  15. Assessing Nanoparticle Toxicity

    NASA Astrophysics Data System (ADS)

    Love, Sara A.; Maurer-Jones, Melissa A.; Thompson, John W.; Lin, Yu-Shen; Haynes, Christy L.

    2012-07-01

    Nanoparticle toxicology, an emergent field, works toward establishing the hazard of nanoparticles, and therefore their potential risk, in light of the increased use and likelihood of exposure. Analytical chemists can provide an essential tool kit for the advancement of this field by exploiting expertise in sample complexity and preparation as well as method and technology development. Herein, we discuss experimental considerations for performing in vitro nanoparticle toxicity studies, with a focus on nanoparticle characterization, relevant model cell systems, and toxicity assay choices. Additionally, we present three case studies (of silver, titanium dioxide, and carbon nanotube toxicity) to highlight the important toxicological considerations of these commonly used nanoparticles.

  16. Cell tracking using nanoparticles.

    PubMed

    Vaccaro, Dennis E; Yang, Meiheng; Weinberg, James S; Reinhardt, Christopher P; Groman, Ernest V

    2008-09-01

    Tracking cells in regenerative medicine is becoming increasingly important for basic cell therapy science, for cell delivery optimization and for accurate biodistribution studies. This report describes nanoparticles that utilize stable-isotope metal labels for multiple detection technologies in preclinical studies. Cells labeled with nanoparticles can be imaged by electron microscopy, fluorescence, and magnetic resonance. The nanoparticle-labeled cells can be quantified by neutron activation, thereby allowing, with the use of standard curves, the determination of the number of labeled cells in tissue samples from in vivo sources. This report describes the characteristics of these nanoparticles and methods for using these nanoparticles to label and track cells.

  17. Reactivity of NHC Alane Adducts towards N-Heterocyclic Carbenes and Cyclic (Alkyl)(amino)carbenes: Ring Expansion, Ring Opening, and Al-H Bond Activation.

    PubMed

    Schneider, Heidi; Hock, Andreas; Bertermann, Rüdiger; Radius, Udo

    2017-09-07

    The synthesis of mono-NHC alane adducts of the type (NHC)⋅AlH3 (NHC=Me2 Im (1), Me2 Im(Me) (2), iPr2 Im (3 and [D3 ]-3), iPr2 Im(Me) (4), Dipp2 Im (10); Im=imidazolin-2-ylidene, Dipp=2,6-diisopropylphenyl) and (NHC)⋅AliBu2 H (NHC=iPr2 Im (11), Dipp2 Im (12)) as well as their reactivity towards different types of carbenes is presented. Although the mono-NHC adducts remained stable at elevated temperatures, ring expansion occurred when (iPr2 Im)⋅AlH3 (3) was treated with a second equivalent of the carbene iPr2 Im to give (iPr2 Im)⋅AlH(RER-iPr2 ImH2 ) (6). In 6, {(iPr2 Im}AlH} is inserted into the NHC ring. In contrast, ring opening was observed with the sterically more demanding Dipp2 Im with the formation of (iPr2 Im)⋅AlH2 (ROR-Dipp2 ImH2 )H2 Al⋅(iPr2 Im) (9). In 9, two {(iPr2 Im)⋅AlH2 } moieties stabilize the ring-opened Dipp2 Im. If two hydridic sites are blocked, the adducts are stable with respect to further ring expansion or ring opening, as exemplified by the adducts (iPr2 Im)⋅AliBu2 H (11) and (Dipp2 Im)⋅AliBu2 H (12). The adducts (NHC)⋅AlH3 and (iPr2 Im)⋅AliBu2 H reacted with cAAC(Me) by insertion of the carbene carbon atom into the Al-H bond to give (NHC)⋅AlH2 /iBu2 (cAAC(Me) H) (13-18) instead of ligand substitution, ring-expansion, or ring-opened products. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Advances in the electrochemical regeneration of aluminum hydride

    NASA Astrophysics Data System (ADS)

    Martínez-Rodríguez, Michael J.; García-Díaz, Brenda L.; Teprovich, Joseph A.; Knight, Douglas A.; Zidan, Ragaiy

    2012-03-01

    In previous work, a reversible cycle that uses electrolysis and catalytic hydrogenation of spent Al(s) for the regeneration of alane (AlH3) was reported. In this study, the electrochemical synthesis of alane is improved. Advances in the electrochemical regeneration of alane have been achieved via the use of lithium aluminum hydride (LiAlH4) and lithium chloride (LiCl). Lithium chloride reacts in a cyclic process and functions as an electro-catalytic additive that enhances the electrochemical process by increasing the cell efficiency and the alane production. Electrochemical techniques are used to show that the increased rate of alane generation is due to the electro-catalytic effect of lithium chloride, rather than an electrolyte enhanced effect.

  19. De-alloyed platinum nanoparticles

    DOEpatents

    Strasser, Peter; Koh, Shirlaine; Mani, Prasanna; Ratndeep, Srivastava

    2011-08-09

    A method of producing de-alloyed nanoparticles. In an embodiment, the method comprises admixing metal precursors, freeze-drying, annealing, and de-alloying the nanoparticles in situ. Further, in an embodiment de-alloyed nanoparticle formed by the method, wherein the nanoparticle further comprises a core-shell arrangement. The nanoparticle is suitable for electrocatalytic processes and devices.

  20. Multifunctional nanoparticles: analytical prospects.

    PubMed

    de Dios, Alejandro Simón; Díaz-García, Marta Elena

    2010-05-07

    Multifunctional nanoparticles are among the most exciting nanomaterials with promising applications in analytical chemistry. These applications include (bio)sensing, (bio)assays, catalysis and separations. Although most of these applications are based on the magnetic, optical and electrochemical properties of multifunctional nanoparticles, other aspects such as the synergistic effect of the functional groups and the amplification effect associated with the nanoscale dimension have also been observed. Considering not only the nature of the raw material but also the shape, there is a huge variety of nanoparticles. In this review only magnetic, quantum dots, gold nanoparticles, carbon and inorganic nanotubes as well as silica, titania and gadolinium oxide nanoparticles are addressed. This review presents a narrative summary on the use of multifunctional nanoparticles for analytical applications, along with a discussion on some critical challenges existing in the field and possible solutions that have been or are being developed to overcome these challenges.

  1. Nanoparticles and direct immunosuppression

    PubMed Central

    Ngobili, Terrika A

    2016-01-01

    Targeting the immune system with nanomaterials is an intensely active area of research. Specifically, the capability to induce immunosuppression is a promising complement for drug delivery and regenerative medicine therapies. Many novel strategies for immunosuppression rely on nanoparticles as delivery vehicles for small-molecule immunosuppressive compounds. As a consequence, efforts in understanding the mechanisms in which nanoparticles directly interact with the immune system have been overshadowed. The immunological activity of nanoparticles is dependent on the physiochemical properties of the nanoparticles and its subsequent cellular internalization. As the underlying factors for these reactions are elucidated, more nanoparticles may be engineered and evaluated for inducing immunosuppression and complementing immunosuppressive drugs. This review will briefly summarize the state-of-the-art and developments in understanding how nanoparticles induce immunosuppressive responses, compare the inherent properties of nanomaterials which induce these immunological reactions, and comment on the potential for using nanomaterials to modulate and control the immune system. PMID:27229901

  2. Stimulus Responsive Nanoparticles

    NASA Technical Reports Server (NTRS)

    Cairns, Darran Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2015-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  3. Stimulus responsive nanoparticles

    NASA Technical Reports Server (NTRS)

    Cairns, Darren Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2013-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  4. Digestive ripening of nanoparticles

    NASA Astrophysics Data System (ADS)

    Irzhak, V. I.

    2017-08-01

    A relatively new method of regulating the size distribution function of nanoparticles—digestive ripening— was described. A hypothetical mechanism of dissolution of nanoparticles was proposed. It includes the effect of the ligand layer on the internal stability of the nanoparticle nucleus: the change in the structure of the ligand layer caused by a decrease in the nanoparticle size determines the kinetics of digestive ripening.

  5. Stimulus Responsive Nanoparticles

    NASA Technical Reports Server (NTRS)

    Cairns, Darran Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)

    2017-01-01

    Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment including a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.

  6. Metallic magnetic nanoparticles.

    PubMed

    Hernando, A; Crespo, P; García, M A

    2005-12-22

    In this paper, we reviewed some relevant aspects of the magnetic properties of metallic nanoparticles with small size (below 4 nm), covering the size effects in nanoparticles of magnetic materials, as well as the appearance of magnetism at the nanoscale in materials that are nonferromagnetic in bulk. These results are distributed along the text that has been organized around three important items: fundamental magnetic properties, different fabrication procedures, and characterization techniques. A general introduction and some experimental results recently obtained in Pd and Au nanoparticles have also been included. Finally, the more promising applications of magnetic nanoparticles in biomedicine are indicated. Special care was taken to complete the literature available on the subject.

  7. Cubic colloidal platinum nanoparticles

    SciTech Connect

    Ahmadi, T.S.; Wang, Z.L.; Henglein, A.; El-Sayed, M.A.

    1996-06-01

    Cubic platinum nanoparticles (4-18 nm) have been synthesized for the first time in solution by the controlled reduction of K{sub 2}PtCl{sub 4} with hydrogen gas in the presence of sodium polyacrylate as a capping material. The nanoparticles are found to have fcc structures, similar to the bulk metal with (100) facets.

  8. Biocompatible nanoparticles and biopolyelectrolytes

    NASA Astrophysics Data System (ADS)

    Zribi, Olena

    The research presented in this manuscript encompasses a merger of two research directions: a study of aqueous nanoparticle colloids and a study of biological polyelectrolytes. The majority of biomedical applications of nanoparticles require stable aqueous colloids of nanoparticles as a starting point. A new one-step method of preparation of aqueous solutions of ultra-fine ferroelectric barium titanate nanoparticles was developed and generalized to the preparation of stable aqueous colloids of semiconductor nanoparticles. This high-energy ball milling technique is low cost, environmentally friendly, and allows for control of nanoparticle size by changing milling time. Aqueous colloids of BaTiO3 nanoparticles are stable over time, maintain ferroelectricity and can be used as second harmonic generating nanoprobes for biomedical imaging. Biopolyelectrolytes exhibit a variety of novel liquid-crystalline phases in aqueous solutions where their electrolytic nature is a driving force behind phase formation. We study medically relevant mixtures of F-actin, DNA and oppositely charged ions (such as multivalent salts and antibiotic drugs) and map out phase diagrams and laws that govern phase transitions. We combine these research directions in studies of the condensation behavior in aqueous solutions of biocompatible nanoparticles and biopolyelectrolytes.

  9. Theoretical exploration of hydrogen loss from Al3H9.

    PubMed

    Nold, Christopher P; Head, John D

    2012-05-03

    The Al(3)H(9) and Al(3)H(7) potential energy surfaces were explored using quantum chemistry calculations to investigate the H(2) loss mechanism from Al(3)H(9), which provide new insights into hydrogen production from bulk alane, [AlH(3)](x), a possible energy storage material. We present results of B3LYP/6-311++G(d,p) calculations for the various Al(3)H(9) and Al(3)H(7) optimized local minima and transition state structures along with some reaction pathways for their interconversion. We find the energy for Al(3)H(9) decomposition into Al(2)H(6) and AlH(3) is slightly lower than that for H(2) loss and Al(3)H(7) formation, but the calculations show that H(2) loss from Al(3)H(9) is a lower energy process than for losing hydrogen from either Al(2)H(6) or AlH(3). We found four transition state structures and reaction pathways for Al(3)H(9) → Al(3)H(7) + H(2), where the lowest energy activation barrier is around 25-73 kJ/mol greater than the experimental value for H(2) loss from bulk alane. Intrinsic reaction coordinate calculations show that the H(2) loss pathway involves considerable rearrangement of the H atom positions around a single Al center. Three of the pathways start with the formation of an AlH(3) moiety, which then enables a terminal H on the AlH(3) to get within 1.1 to 1.2 Å of a nearby bridging H atom. The bridging and terminal H atoms eventually combine to form H(2) and leave Al(3)H(9). One implication of these H(2) loss reaction pathways is that, since the H atoms in bulk alanes are all at bridging positions, if a similar H(2) loss mechanism were to apply to bulk alane, then H(2) loss would most likely occur on the bulk alane surface or at a defect site where there should be more terminal H atoms available for reaction with nearby bridging H atoms.

  10. Industrial applications of nanoparticles.

    PubMed

    Stark, W J; Stoessel, P R; Wohlleben, W; Hafner, A

    2015-08-21

    Research efforts in the past two decades have resulted in thousands of potential application areas for nanoparticles - which materials have become industrially relevant? Where are sustainable applications of nanoparticles replacing traditional processing and materials? This tutorial review starts with a brief analysis on what makes nanoparticles attractive to chemical product design. The article highlights established industrial applications of nanoparticles and then moves to rapidly emerging applications in the chemical industry and discusses future research directions. Contributions from large companies, academia and high-tech start-ups are used to elucidate where academic nanoparticle research has revolutionized industry practice. A nanomaterial-focused analysis discusses new trends, such as particles with an identity, and the influence of modern instrument advances in the development of novel industrial products.

  11. Green Luminescent Copper Nanoparticles

    NASA Astrophysics Data System (ADS)

    Suresh, Y.; Annapurna, S.; Bhikshamaiah, G.; Singh, A. K.

    2016-09-01

    Copper nanoparticles are synthesized by a green chemical reduction method using Gum Kondagogu extract as stabilizer. The as-prepared powder samples are characterized by Transmission Electron Microscopy (TEM), Small Angle X-Ray Scattering (SAXS), UV-Visible Spectroscopy, X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) techniques. The as-prepared copper nanoparticles are found to be FCC crystalline and nearly monodispersed with particles size 19 nm. Photoluminescence (PL) measurement showed strong green visible emission and PL intensity was found enhanced with the presence of natural extract on copper nanoparticle surface. The increase in the PL intensity was mainly due to copper nanoparticles. Photoluminescence spectra of copper nanoparticles show an emission peak at 430 nm when illuminated at 325 nm.

  12. Nanoparticles: potential biomarker harvesters.

    PubMed

    Geho, David H; Jones, Clinton D; Petricoin, Emanuel F; Liotta, Lance A

    2006-02-01

    A previously untapped bank of information resides within the low molecular weight proteomic fraction of blood. Intensive efforts are underway to harness this information so that it can be used for early diagnosis of diseases such as cancer. The physicochemical malleability and high surface areas of nanoparticle surfaces make them ideal candidates for developing biomarker harvesting platforms. Given the variety of engineering strategies afforded through nanoparticle technologies, a significant goal is to tailor nanoparticle surfaces to selectively bind a subset of biomarkers, sequestering them for later study using high sensitivity proteomic tests. To date, applications of nanoparticles have largely focused on imaging systems and drug delivery vectors. As such, biomarker harvesting is an underutilized application of nanoparticle technology and is an area of nanotechnology research that will likely undergo substantial growth.

  13. Energy breathing of nanoparticles

    NASA Astrophysics Data System (ADS)

    Dynich, Raman A.

    2015-06-01

    The paper considers the energy exchange process of the electromagnetic wave with a spherical metal nanoparticle. Based on the account of the temporal dependencies of electric and magnetic fields, the author presents an analytical dependence of the energy flow passing through the spherical surface. It is shown that the electromagnetic energy, localized in metal nanoparticles, is not a stationary value and periodically varies with time. A consequence of the energy nonstationarity is a nonradiating exit of the electromagnetic energy out of the nanoparticle. During the time equal to the period of wave oscillations, the electromagnetic energy is penetrating twice into the particle and quits it twice. The particle warms up because of the difference in the incoming and outgoing energies. Such "energy breathing" is presented for spherical Ag and Au nanoparticles with radii of 10 i 33 nm, respectively. Calculations were conducted for these nanoparticles embedded into the cell cytoplasm near the frequencies of their surface plasmon resonances.

  14. Single Nanoparticle Plasmonic Sensors

    PubMed Central

    Sriram, Manish; Zong, Kelly; Vivekchand, S. R. C.; Gooding, J. Justin

    2015-01-01

    The adoption of plasmonic nanomaterials in optical sensors, coupled with the advances in detection techniques, has opened the way for biosensing with single plasmonic particles. Single nanoparticle sensors offer the potential to analyse biochemical interactions at a single-molecule level, thereby allowing us to capture even more information than ensemble measurements. We introduce the concepts behind single nanoparticle sensing and how the localised surface plasmon resonances of these nanoparticles are dependent upon their materials, shape and size. Then we outline the different synthetic approaches, like citrate reduction, seed-mediated and seedless growth, that enable the synthesis of gold and silver nanospheres, nanorods, nanostars, nanoprisms and other nanostructures with tunable sizes. Further, we go into the aspects related to purification and functionalisation of nanoparticles, prior to the fabrication of sensing surfaces. Finally, the recent developments in single nanoparticle detection, spectroscopy and sensing applications are discussed. PMID:26473866

  15. Reaction of the Primary Alane (2,4,6-t-Bu(3)H(2)C(6)AlH(2))(2) with Nitriles, Isonitriles, and Primary Amines.

    PubMed

    Wehmschulte, Rudolf J.; Power, Philip P.

    1998-12-28

    The reactions of the sterically encumbered primary alane (MesAlH(2))(2) (Mes = C(6)H(2)-2,4,6-t-Bu(3)) with the nitriles t-BuCN, MesCN (Mes = C(6)H(2)-2,4,6-Me(3)) or MeCN lead eventually to dimeric amido alane products in which one of the ortho t-Bu groups of the Mes ligand is metalated and the nitrile is reduced to the amide ligand N(H)CH(2)R (R = t-Bu, Mes, or Me). The compounds (R = t-Bu, 2 (cis), 3 (trans); Mes, 4 (cis), 5 (trans); Me, 6 (cis)) have been isolated and characterized spectroscopically and also by X-ray crystallography in the cases of 4 and 5. The intermediate, dimeric iminato complex [MesAl(H){&mgr;(2)-NC(H)t-Bu}](2) (1), can also be isolated under carefully controlled, mild conditions. Reaction of (MesAlH(2))(2) with the isonitrile t-BuNC affords the cyclic species {MesAlN(t-Bu)CH(2)}(2) (7) featuring a six-membered (AlNC)(2) ring which, when heated, affords the cyclometalated species (8). Recognition that the products 2-6 and 8 were derivatives of primary amides led to an investigation of synthetic approaches to these product types via the direct reaction of (MesAlH(2))(2) with some primary amines. Treatment of (MesAlH(2))(2) with H(2)NCH(2)Mes affords the dimeric amido alane [Mes(H)Al{&mgr;(2)-N(H)CH(2)Mes}](2) as a mixture of trans (9) and cis (10) isomers. Further heating of 9 and 10 affords the ortho-metalated compounds 4 and 5. The reaction of (MesAlH(2))(2) with H(2)NSiPh(3) furnishes the bis amido aluminum compound MesAl{N(H)SiPh(3)}(2) (11) and [Mes(H)Al{N(H)SiPh(3)}](2). The latter yields the dimeric imide {MesAlNSiPh(3)}(2) (12) at elevated temperature.

  16. An insight into the process and mechanism of a mechanically activated reaction for synthesizing AlH3 nano-composites.

    PubMed

    Duan, Congwen; Hu, Lianxi; Sun, Yu; Zhou, Haiping; Yu, Huan

    2015-10-07

    The reaction pathway as well as the mechanism of the solid state reaction between MgH2 and AlCl3 has been a mystery so far. Based on SEM, TEM and NMR (Nuclear Magnetic Resonance) analyses, an amorphous intermediate (AlH6)n was preferentially formed and recrystallized as a γ phase at the final stage of the reaction. As a novel finding, this research provides a deep insight into the process and mechanism of this mechanically activated reaction.

  17. Nanoparticle Approaches against Bacterial Infections

    PubMed Central

    Gao, Weiwei; Thamphiwatana, Soracha; Angsantikul, Pavimol; Zhang, Liangfang

    2014-01-01

    Despite the wide success of antibiotics, the treatment of bacterial infection still faces significant challenges, particularly the emergence of antibiotic resistance. As a result, nanoparticle drug delivery platforms including liposomes, polymeric nanoparticles, dendrimers, and various inorganic nanoparticles have been increasingly exploited to enhance the therapeutic effectiveness of existing antibiotics. This review focuses on areas where nanoparticle approaches hold significant potential to advance the treatment of bacterial infection. These areas include targeted antibiotic delivery, environmentally responsive antibiotic delivery, combinatorial antibiotic delivery, nanoparticle-enabled antibacterial vaccination, and nanoparticle-based bacterial detection. In each area we highlight the innovative antimicrobial nanoparticle platforms and review their progress made against bacterial infections. PMID:25044325

  18. Shear thinning of nanoparticle suspensions.

    SciTech Connect

    Grest, Gary Stephen; Petersen, Matthew K.; in't Veld, Pieter J.

    2008-08-01

    Results of large scale non-equilibrium molecular dynamics (NEMD) simulations are presented for nanoparticles in an explicit solvent. The nanoparticles are modeled as a uniform distribution of Lennard-Jones particles, while the solvent is represented by standard Lennard-Jones particles. Here we present results for the shear rheology of spherical nanoparticles of size 5 to 20 times that of the solvent for a range of nanoparticle volume fractions and interactions. Results from NEMD simulations suggest that for strongly interacting nanoparticle that form a colloidal gel, the shear rheology of the suspension depends only weakly on the size of the nanoparticle, even for nanoparticles as small as 5 times that of the solvent. However for hard sphere-like colloids the size of the nanoparticles strongly affects the shear rheology. The shear rheology for dumbbell nanoparticles made of two fused spheres is also compared to spherical nanoparticles and found to be similar except at very high volume fractions.

  19. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles.

    PubMed

    Yang, Yongkun; Burkhard, Peter

    2012-10-31

    Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs) to encapsulate gold nanoparticles. The protein nanoparticles are formed upon self-assembly of a protein chain that is composed of a pentameric coiled-coil domain at the N-terminus and trimeric coiled-coil domain at the C-terminus. The self-assembling protein nanoparticles form a central cavity of about 10 nm in size, which is ideal for the encapsulation of gold nanoparticles with similar sizes. We have used SAPNs to encapsulate several commercially available gold nanoparticles. The hydrodynamic size and the surface coating of gold nanoparticles are two important factors influencing successful encapsulation by the SAPNs. Gold nanoparticles with a hydrodynamic size of less than 15 nm can successfully be encapsulated. Gold nanoparticles with citrate coating appear to have stronger interactions with the proteins, which can interfere with the formation of regular protein nanoparticles. Upon encapsulation gold nanoparticles with polymer coating interfere less strongly with the ability of the SAPNs to assemble into nanoparticles. Although the central cavity of the SAPNs carries an overall charge, the electrostatic interaction appears to be less critical for the efficient encapsulation of gold nanoparticles into the protein nanoparticles. The SAPNs can be used to encapsulate gold nanoparticles. The SAPNs can be further functionalized by engineering functional peptides or proteins to either their N- or C-termini. Therefore encapsulation of gold nanoparticles into SAPNs can provide a useful platform to

  20. Encapsulation of gold nanoparticles into self-assembling protein nanoparticles

    PubMed Central

    2012-01-01

    Background Gold nanoparticles are useful tools for biological applications due to their attractive physical and chemical properties. Their applications can be further expanded when they are functionalized with biological molecules. The biological molecules not only provide the interfaces for interactions between nanoparticles and biological environment, but also contribute their biological functions to the nanoparticles. Therefore, we used self-assembling protein nanoparticles (SAPNs) to encapsulate gold nanoparticles. The protein nanoparticles are formed upon self-assembly of a protein chain that is composed of a pentameric coiled-coil domain at the N-terminus and trimeric coiled-coil domain at the C-terminus. The self-assembling protein nanoparticles form a central cavity of about 10 nm in size, which is ideal for the encapsulation of gold nanoparticles with similar sizes. Results We have used SAPNs to encapsulate several commercially available gold nanoparticles. The hydrodynamic size and the surface coating of gold nanoparticles are two important factors influencing successful encapsulation by the SAPNs. Gold nanoparticles with a hydrodynamic size of less than 15 nm can successfully be encapsulated. Gold nanoparticles with citrate coating appear to have stronger interactions with the proteins, which can interfere with the formation of regular protein nanoparticles. Upon encapsulation gold nanoparticles with polymer coating interfere less strongly with the ability of the SAPNs to assemble into nanoparticles. Although the central cavity of the SAPNs carries an overall charge, the electrostatic interaction appears to be less critical for the efficient encapsulation of gold nanoparticles into the protein nanoparticles. Conclusions The SAPNs can be used to encapsulate gold nanoparticles. The SAPNs can be further functionalized by engineering functional peptides or proteins to either their N- or C-termini. Therefore encapsulation of gold nanoparticles into SAPNs can

  1. Nanoparticle flotation collectors II: the role of nanoparticle hydrophobicity.

    PubMed

    Yang, Songtao; Pelton, Robert

    2011-09-20

    The ability of polystyrene nanoparticles to facilitate the froth flotation of glass beads was correlated to the hydrophobicity of the nanoparticles. Contact angle measurements were used to probe the hydrophobicity of hydrophilic glass surfaces decorated with hydrophobic nanoparticles. Both sessile water drop advancing angles, θ(a), and attached air bubble receding angle measurements, θ(r), were performed. For glass surfaces saturated with adsorbed nanoparticles, flotation recovery, a measure of flotation efficiency, increased with increasing values of each type of contact angle. As expected, the advancing water contact angle on nanoparticle-decorated, dry glass surfaces increased with surface coverage, the area fraction of glass covered with nanoparticles. However, the nanoparticles were far more effective at raising the contact angle than the Cassie-Baxter prediction, suggesting that with higher nanoparticle coverages the water did not completely wet the glass surfaces between the nanoparticles. A series of polystyrene nanoparticles was prepared to cover a range of surface energies. Water contact angle measurements, θ(np), on smooth polymer films formed from organic solutions of dissolved nanoparticles were used to rank the nanoparticles in terms of hydrophobicity. Glass spheres were saturated with adsorbed nanoparticles and were isolated by flotation. The minimum nanoparticle water contact angle to give high flotation recovery was in the range of 51° < θ(np(min)) ≤ 85°.

  2. Gas Phase Nanoparticle Synthesis

    NASA Astrophysics Data System (ADS)

    Granqvist, Claes; Kish, Laszlo; Marlow, William

    This book deals with gas-phase nanoparticle synthesis and is intended for researchers and research students in nanomaterials science and engineering, condensed matter physics and chemistry, and aerosol science. Gas-phase nanoparticle synthesis is instrumental to nanotechnology - a field in current focus that raises hopes for environmentally benign, resource-lean manufacturing. Nanoparticles can be produced by many physical, chemical, and even biological routes. Gas-phase synthesis is particularly interesting since one can achieve accurate manufacturing control and hence industrial viability.

  3. Resonant halide perovskite nanoparticles

    NASA Astrophysics Data System (ADS)

    Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

    2017-09-01

    The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

  4. DNA Functionalization of Nanoparticles.

    PubMed

    Lu, Fang; Gang, Oleg

    2017-01-01

    DNA-nanoparticle conjugates are hybrid nanoscale objects that integrate different types of DNA molecules and inorganic nanoparticles with a typical architecture of a DNA shell around an inorganic core. Such incorporation provides particles with unique properties of DNA, addressability and recognition, but, at the same time, allows exploiting the properties of the particle's inorganic core. Thus, these hybrid nano-objects are advantageous for rational fabrication of functional materials and for biomedical applications. Here, we describe several established DNA functionalization procedures for different types of surface ligands and nanoparticle core materials.

  5. Toxicity of therapeutic nanoparticles.

    PubMed

    Maurer-Jones, Melissa A; Bantz, Kyle C; Love, Sara A; Marquis, Bryce J; Haynes, Christy L

    2009-02-01

    A total of six nanotherapeutic formulations are already approved for medical use and more are in the approval pipeline currently. Despite the massive research effort in nanotherapeutic materials, there is relatively little information about the toxicity of these materials or the tools needed to assess this toxicity. Recently, the scientific community has begun to respond to the paucity of information by investing in the field of nanoparticle toxicology. This review is intended to provide an overview of the techniques needed to assess toxicity of these therapeutic nanoparticles and to summarize the current state of the field. We begin with background on the toxicological assessment techniques used currently as well as considerations in nanoparticle dosing. The toxicological research overview is divided into the most common applications of therapeutic nanoparticles: drug delivery, photodynamic therapy and bioimaging. We end with a perspective section discussing the current technological gaps and promising research aimed at addressing those gaps.

  6. Magnetic nanoparticle temperature estimation.

    PubMed

    Weaver, John B; Rauwerdink, Adam M; Hansen, Eric W

    2009-05-01

    The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 degree K between 20 and 50 degrees C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution.

  7. Magnetic nanoparticle temperature estimation

    PubMed Central

    Weaver, John B.; Rauwerdink, Adam M.; Hansen, Eric W.

    2009-01-01

    The authors present a method of measuring the temperature of magnetic nanoparticles that can be adapted to provide in vivo temperature maps. Many of the minimally invasive therapies that promise to reduce health care costs and improve patient outcomes heat tissue to very specific temperatures to be effective. Measurements are required because physiological cooling, primarily blood flow, makes the temperature difficult to predict a priori. The ratio of the fifth and third harmonics of the magnetization generated by magnetic nanoparticles in a sinusoidal field is used to generate a calibration curve and to subsequently estimate the temperature. The calibration curve is obtained by varying the amplitude of the sinusoidal field. The temperature can then be estimated from any subsequent measurement of the ratio. The accuracy was 0.3 °K between 20 and 50 °C using the current apparatus and half-second measurements. The method is independent of nanoparticle concentration and nanoparticle size distribution. PMID:19544801

  8. Theoretical Approaches to Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kempa, Krzysztof

    Nanoparticles can be viewed as wave resonators. Involved waves are, for example, carrier waves, plasmon waves, polariton waves, etc. A few examples of successful theoretical treatments that follow this approach are given. In one, an effective medium theory of a nanoparticle composite is presented. In another, plasmon polaritonic solutions allow to extend concepts of radio technology, such as an antenna and a coaxial transmission line, to the visible frequency range.

  9. Externally modulated theranostic nanoparticles

    PubMed Central

    Urban, Cordula; Urban, Alexander S.; Charron, Heather; Joshi, Amit

    2013-01-01

    Externally modulated nanoparticles comprise a rapidly advancing class of cancer nanotherapeutics, which combine the favorable tumor accumulation of nanoparticles, with external spatio-temporal control on therapy delivery via optical, magnetic, or ultrasound modalities. The local control on therapy enables higher tumor treatment efficacy, while simultaneously reducing off-target effects. The nanoparticle interactions with external fields have an additional advantage of frequently generating an imaging signal, and thus such agents provide theranostic (both diagnostic and therapeutic) capabilities. In this review, we classify the emerging externally modulated theranostic nanoparticles according to the mode of external control and describe the physiochemical mechanisms underlying the external control of therapy, and illustrate the major embodiments of nanoparticles in each class with proven biological efficacy: (I) electromagnetic radiation in visible and near-infrared range is being exploited for gold based and carbon nanostructures with tunable surface plasmon resonance (SPR) for imaging and photothermal therapy (PTT) of cancer, photochemistry based manipulations are employed for light sensitive liposomes and porphyrin based nanoparticles; (II) Magnetic field based manipulations are being developed for iron-oxide based nanostructures for magnetic resonance imaging (MRI) and magnetothermal therapy; (III) ultrasound based methods are primarily being employed to increase delivery of conventional drugs and nanotherapeutics to tumor sites. PMID:24834381

  10. Antifungal nanoparticles and surfaces.

    PubMed

    Paulo, Cristiana S O; Vidal, Maria; Ferreira, Lino S

    2010-10-11

    Nosocomial fungal infections, an increasing healthcare concern worldwide, are often associated with medical devices. We have developed antifungal nanoparticle conjugates that can act in suspension or attach to a surface, efficiently killing fungi. For that purpose, we immobilized covalently amphotericin B (AmB), a potent antifungal agent approved by the FDA, widely used in clinical practice and effective against a large spectrum of fungi, into silica nanoparticles. These antifungal nanoparticle conjugates are fungicidal against several strains of Candida sp., mainly by contact. In addition, they can be reused up to 5 cycles without losing their activity. Our results show that the antifungal nanoparticle conjugates are more fungistatic and fungicidal than 10 nm colloidal silver. The antifungal activity of the antifungal nanoparticle conjugates is maintained when they are immobilized on a surface using a chemical adhesive formed by polydopamine. The antifungal nanocoatings have no hemolytic or cytotoxic effect against red blood cells and blood mononuclear cells, respectively. Surfaces coated with these antifungal nanoparticle conjugates can be very useful to render medical devices with antifungal properties.

  11. Imaging through plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Tanzid, Mehbuba; Sobhani, Ali; DeSantis, Christopher J.; Cui, Yao; Hogan, Nathaniel J.; Samaniego, Adam; Veeraraghavan, Ashok; Halas, Naomi J.

    2016-05-01

    The optical properties of metallic nanoparticles with plasmon resonances have been studied extensively, typically by measuring the transmission of light, as a function of wavelength, through a nanoparticle suspension. One question that has not yet been addressed, however, is how an image is transmitted through such a suspension of absorber-scatterers, in other words, how the various spatial frequencies are attenuated as they pass through the nanoparticle host medium. Here, we examine how the optical properties of a suspension of plasmonic nanoparticles affect the transmitted image. We use two distinct ways to assess transmitted image quality: the structural similarity index (SSIM), a perceptual distortion metric based on the human visual system, and the modulation transfer function (MTF), which assesses the resolvable spatial frequencies. We show that perceived image quality, as well as spatial resolution, are both dependent on the scattering and absorption cross-sections of the constituent nanoparticles. Surprisingly, we observe a nonlinear dependence of image quality on optical density by varying optical path length and nanoparticle concentration. This work is a first step toward understanding the requirements for visualizing and resolving objects through media consisting of subwavelength absorber-scatterer structures, an approach that should also prove useful in the assessment of metamaterial or metasurface-based optical imaging systems.

  12. Externally modulated theranostic nanoparticles.

    PubMed

    Urban, Cordula; Urban, Alexander S; Charron, Heather; Joshi, Amit

    2013-08-01

    Externally modulated nanoparticles comprise a rapidly advancing class of cancer nanotherapeutics, which combine the favorable tumor accumulation of nanoparticles, with external spatio-temporal control on therapy delivery via optical, magnetic, or ultrasound modalities. The local control on therapy enables higher tumor treatment efficacy, while simultaneously reducing off-target effects. The nanoparticle interactions with external fields have an additional advantage of frequently generating an imaging signal, and thus such agents provide theranostic (both diagnostic and therapeutic) capabilities. In this review, we classify the emerging externally modulated theranostic nanoparticles according to the mode of external control and describe the physiochemical mechanisms underlying the external control of therapy, and illustrate the major embodiments of nanoparticles in each class with proven biological efficacy: (I) electromagnetic radiation in visible and near-infrared range is being exploited for gold based and carbon nanostructures with tunable surface plasmon resonance (SPR) for imaging and photothermal therapy (PTT) of cancer, photochemistry based manipulations are employed for light sensitive liposomes and porphyrin based nanoparticles; (II) Magnetic field based manipulations are being developed for iron-oxide based nanostructures for magnetic resonance imaging (MRI) and magnetothermal therapy; (III) ultrasound based methods are primarily being employed to increase delivery of conventional drugs and nanotherapeutics to tumor sites.

  13. Imaging through plasmonic nanoparticles

    PubMed Central

    Tanzid, Mehbuba; Sobhani, Ali; DeSantis, Christopher J.; Cui, Yao; Hogan, Nathaniel J.; Samaniego, Adam; Veeraraghavan, Ashok; Halas, Naomi J.

    2016-01-01

    The optical properties of metallic nanoparticles with plasmon resonances have been studied extensively, typically by measuring the transmission of light, as a function of wavelength, through a nanoparticle suspension. One question that has not yet been addressed, however, is how an image is transmitted through such a suspension of absorber-scatterers, in other words, how the various spatial frequencies are attenuated as they pass through the nanoparticle host medium. Here, we examine how the optical properties of a suspension of plasmonic nanoparticles affect the transmitted image. We use two distinct ways to assess transmitted image quality: the structural similarity index (SSIM), a perceptual distortion metric based on the human visual system, and the modulation transfer function (MTF), which assesses the resolvable spatial frequencies. We show that perceived image quality, as well as spatial resolution, are both dependent on the scattering and absorption cross-sections of the constituent nanoparticles. Surprisingly, we observe a nonlinear dependence of image quality on optical density by varying optical path length and nanoparticle concentration. This work is a first step toward understanding the requirements for visualizing and resolving objects through media consisting of subwavelength absorber-scatterer structures, an approach that should also prove useful in the assessment of metamaterial or metasurface-based optical imaging systems. PMID:27140618

  14. Introduction to metallic nanoparticles

    PubMed Central

    Mody, Vicky V.; Siwale, Rodney; Singh, Ajay; Mody, Hardik R.

    2010-01-01

    Metallic nanoparticles have fascinated scientist for over a century and are now heavily utilized in biomedical sciences and engineering. They are a focus of interest because of their huge potential in nanotechnology. Today these materials can be synthesized and modified with various chemical functional groups which allow them to be conjugated with antibodies, ligands, and drugs of interest and thus opening a wide range of potential applications in biotechnology, magnetic separation, and preconcentration of target analytes, targeted drug delivery, and vehicles for gene and drug delivery and more importantly diagnostic imaging. Moreover, various imaging modalities have been developed over the period of time such as MRI, CT, PET, ultrasound, SERS, and optical imaging as an aid to image various disease states. These imaging modalities differ in both techniques and instrumentation and more importantly require a contrast agent with unique physiochemical properties. This led to the invention of various nanoparticulated contrast agent such as magnetic nanoparticles (Fe3O4), gold, and silver nanoparticles for their application in these imaging modalities. In addition, to use various imaging techniques in tandem newer multifunctional nanoshells and nanocages have been developed. Thus in this review article, we aim to provide an introduction to magnetic nanoparticles (Fe3O4), gold nanoparticles, nanoshells and nanocages, and silver nanoparticles followed by their synthesis, physiochemical properties, and citing some recent applications in the diagnostic imaging and therapy of cancer. PMID:21180459

  15. Heteroaggregation of cerium oxide nanoparticles and nanoparticles of pyrolyzed biomass

    USDA-ARS?s Scientific Manuscript database

    Heteroaggregation with indigenous particles is an important process controlling the mobility of engineered nanomaterials in the environment. We studied heteroaggregation of cerium oxide nanoparticles (n-CeO2), which are widely used commercially, with nanoparticles of pyrogenic carbonaceous material ...

  16. MEASUREMENT OF NANOPARTICLES IN WATER

    EPA Science Inventory

    Measuring nanoparticles in water differs from traditional dissolved solute measurement in several ways. The most salient difference is that nanoparticles are colloids rather than solutes and therefore are subject to the interparticle interactions (mainly electrostatic and Van de...

  17. MEASUREMENT OF NANOPARTICLES IN WATER

    EPA Science Inventory

    Measuring nanoparticles in water differs from traditional dissolved solute measurement in several ways. The most salient difference is that nanoparticles are colloids rather than solutes and therefore are subject to the interparticle interactions (mainly electrostatic and Van de...

  18. Direct hierarchical assembly of nanoparticles

    DOEpatents

    Xu, Ting; Zhao, Yue; Thorkelsson, Kari

    2014-07-22

    The present invention provides hierarchical assemblies of a block copolymer, a bifunctional linking compound and a nanoparticle. The block copolymers form one micro-domain and the nanoparticles another micro-domain.

  19. Polymer and spherical nanoparticle diffusion in nanocomposites

    NASA Astrophysics Data System (ADS)

    Karatrantos, Argyrios; Composto, Russell J.; Winey, Karen I.; Clarke, Nigel

    2017-05-01

    Nanoparticle and polymer dynamics in nanocomposites containing spherical nanoparticles were investigated by means of molecular dynamics simulations. We show that the polymer diffusivity decreases with nanoparticle loading due to an increase of the interfacial area created by nanoparticles, in the polymer matrix. We show that small sized nanoparticles can diffuse much faster than that predicted from the Stokes-Einstein relation in the dilute regime. We show that the nanoparticle diffusivity decreases at higher nanoparticle loading due to nanoparticle-polymer interface. Increase of the nanoparticle radius slows the nanoparticle diffusion.

  20. Nanoparticles for molecular imaging.

    PubMed

    Sheng, Yang; Liao, Lun De; Thakor, Nitish V; Tan, Mei Chee

    2014-10-01

    Imaging techniques have been instrumental in the visualization of fundamental biological processes, identification and diagnosis of diseased states and the development of structure-function relationships at the cellular, tissue and anatomical levels. Together with the advancements made in imaging techniques, complementary chemical compounds, also known as imaging probes or contrast agents, are developed to improve the visibility of the image by enhancing sensitivity, and for the identification and quantitation of specific molecular species or structures. Extensive studies have been conducted to explore the use of inorganic nanoparticles which exhibit magnetic and optical properties unique to the nano regime so as to enhance the signals sensitivity for magnetic resonance and fluorescent imaging. These physical properties are tailored by controlling the size, shape and surface properties of nanoparticles. In addition, surface modification of nanoparticles is often required to improve its stability, compatibility and functionality. Surfactants, surface-active agents, have been used to engineer the surface characteristics of nanoparticles to improved particle stability and functionality. Surfactants enhance nanoparticle stability through the reduction of surface energy, and by acting as a barrier to agglomeration through either steric hindrance or repulsive electrostatic forces. Coupling of nanoparticles with biomolecules such as antibodies or tumor targeting peptides are enabled by the presence of functional groups (e.g., carboxyl or amine groups) on surfactants. This paper provides an overview of the chemistry underlying the synthesis and surface modification of nanomaterials together with a discussion on how the physical properties (e.g., magnetic, absorption and luminescent) can be controlled. The applications of these nanoparticles for magnetic resonance, fluorescent and photoacoustic imaging techniques that do not rely on ionizing radiation are also covered in

  1. Clinically Approved Nanoparticle Imaging Agents

    PubMed Central

    Thakor, Avnesh S.; Jokerst, Jesse V.; Ghanouni, Pejman; Campbell, Jos L.; Mittra, Erik

    2016-01-01

    Nanoparticles are a new class of imaging agent used for both anatomic and molecular imaging. Nanoparticle-based imaging exploits the signal intensity, stability, and biodistribution behavior of submicron-diameter molecular imaging agents. This review focuses on nanoparticles used in human medical imaging, with an emphasis on radionuclide imaging and MRI. Newer nanoparticle platforms are also discussed in relation to theranostic and multimodal uses. PMID:27738007

  2. Chemistry for oncotheranostic gold nanoparticles.

    PubMed

    Trouiller, Anne Juliette; Hebié, Seydou; El Bahhaj, Fatima; Napporn, Teko W; Bertrand, Philippe

    2015-06-24

    This review presents in a comprehensive ways the chemical methods used to functionalize gold nanoparticles with focus on anti-cancer applications. The review covers the parameters required for the synthesis gold nanoparticles with defined shapes and sizes, method for targeted delivery in tumours, and selected examples of anti-cancers compounds delivered with gold nanoparticles. A short survey of bioassays for oncology based on gold nanoparticles is also presented.

  3. Evaluation of nanoparticle-ligand distributions to determine nanoparticle concentration.

    PubMed

    Uddayasankar, Uvaraj; Shergill, Ravi T; Krull, Ulrich J

    2015-01-20

    The concentration of nanoparticles in solution is an important, yet challenging, parameter to quantify. In this work, a facile strategy for the determination of nanoparticle concentration is presented. The method relies on the quantitative analysis of the inherent distribution of nanoparticle-ligand conjugates that are generated when nanoparticles are functionalized with ligands. Validation of the method was accomplished by applying it to gold nanoparticles and semiconductor nanoparticles (CdSe/ZnS; core/shell). Poly(ethylene glycol) based ligands, with functional groups that quantitatively react with the nanoparticles, were incubated with the nanoparticles at varying equivalences. Agarose gel electrophoresis was subsequently used to separate and quantify the nanoparticle-ligand conjugates of varying valences. The distribution in the nanoparticle-ligand conjugates agreed well with that predicted by the Poisson model. A protocol was then developed, where a series of only eight different ligand amounts could provide an estimate of the nanoparticle concentration that spans 3 orders of magnitude (1 μM to 1 mM). For the gold nanoparticles and semiconductor nanoparticles, the measured concentrations were found to deviate by only 7% and 2%, respectively, from those determined by UV-vis spectroscopy. The precision of the assay was evaluated, resulting in a coefficient of variation of 5-7%. Finally, the protocol was used to determine the extinction coefficient of alloyed semiconductor nanoparticles (CdSxSe1-x/ZnS), for which a reliable estimate is currently unavailable, of three different emission wavelengths (525, 575, and 630 nm). The extinction coefficient of the nanoparticles of all emission wavelengths was similar and was found to be 2.1 × 10(5) M(-1)cm(-1).

  4. Lactobacillusassisted synthesis of titanium nanoparticles

    PubMed Central

    2007-01-01

    An eco-friendlylactobacillussp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40–60 nm are found.

  5. Progress Toward Clonable Inorganic Nanoparticles

    PubMed Central

    Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth; Ackerson, Christopher J.

    2015-01-01

    Pseudomonas moraviensis stanleyae was recently isolated from the roots of the Selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32− in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32− (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32− concentration, varying in size form 5nm diameter when formed at 1.0 μM [SeO32−] to 50nm maximum diameter when formed at 100 μM [SeO32−]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site. PMID:26350616

  6. Gold Nanoparticles Cytotoxicity

    NASA Astrophysics Data System (ADS)

    Mironava, Tatsiana

    Over the last two decades gold nanoparticles (AuNPs) have been used for many scientific applications and have attracted attention due to the specific chemical, electronic and optical size dependent properties that make them very promising agents in many fields such as medicine, imagine techniques and electronics. More specifically, biocompatible gold nanoparticles have a huge potential for use as the contrast augmentation agent in X-ray Computed Tomography and Photo Acoustic Tomography for early tumor diagnostic as well these nanoparticles are extensively researched for enhancing the targeted cancer treatment effectiveness such as photo-thermal and radiotherapy. In most biomedical applications biocompatible gold nanoparticles are labeled with specific tumor or other pathology targeting antibodies and used for site specific drug delivery. However, even though gold nanoparticles poses very high level of anti cancer properties, the question of their cytotoxicity ones they are released in normal tissue has to be researched. Moreover, the huge amount of industrially produced gold nanoparticles raises the question of these particles being a health hazard, since the penetration is fairly easy for the "nano" size substances. This study focuses on the effect of AuNPs on a human skin tissue, since it is fall in both categories -- the side effects for biomedical applications and industrial workers and users' exposure during production and handling. Therefore, in the present project, gold nanoparticles stabilized with the biocompatible agent citric acid were generated and characterized by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The cytotoxic effect of AuNPs release to healthy skin tissue was modeled on 3 different cell types: human keratinocytes, human dermal fibroblasts, and human adipose derived stromal (ADS) cells. The AuNPs localization inside the cell was found to be cell type dependent. Overall cytotoxicity was found to be dependent

  7. Gold Nanoparticle Microwave Synthesis

    SciTech Connect

    Krantz, Kelsie E.; Christian, Jonathan H.; Coopersmith, Kaitlin; Washington, II, Aaron L.; Murph, Simona H.

    2016-07-27

    At the nanometer scale, numerous compounds display different properties than those found in bulk material that can prove useful in areas such as medicinal chemistry. Gold nanoparticles, for example, display promise in newly developed hyperthermia therapies for cancer treatment. Currently, gold nanoparticle synthesis is performed via the hot injection technique which has large variability in final particle size and a longer reaction time. One underdeveloped area by which these particles could be produced is through microwave synthesis. To initiate heating, microwaves agitate polar molecules creating a vibration that gives off the heat energy needed. Previous studies have used microwaves for gold nanoparticle synthesis; however, polar solvents were used that partially absorbed incident microwaves, leading to partial thermal heating of the sample rather than taking full advantage of the microwave to solely heat the gold nanoparticle precursors in a non-polar solution. Through this project, microwaves were utilized as the sole heat source, and non-polar solvents were used to explore the effects of microwave heating only as pertains to the precursor material. Our findings show that the use of non-polar solvents allows for more rapid heating as compared to polar solvents, and a reduction in reaction time from 10 minutes to 1 minute; this maximizes the efficiency of the reaction, and allows for reproducibility in the size/shape of the fabricated nanoparticles.

  8. Virus templated metallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Aljabali, Alaa A. A.; Barclay, J. Elaine; Lomonossoff, George P.; Evans, David J.

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. <=35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron. Electronic supplementary information (ESI) available: Additional experimental detail, agarose gel electrophoresis results, energy dispersive X-ray spectra, ζ-potential measurements, dynamic light scattering data, nanoparticle tracking analysis and an atomic force microscopy image of Ni-CPMV. See DOI: 10.1039/c0nr00525h

  9. Understanding nanoparticle-mediated nucleation pathways of anisotropic nanoparticles

    NASA Astrophysics Data System (ADS)

    Laramy, Christine R.; Fong, Lam-Kiu; Jones, Matthew R.; O'Brien, Matthew N.; Schatz, George C.; Mirkin, Chad A.

    2017-09-01

    Several seed-mediated syntheses of low symmetry anisotropic nanoparticles yield broad product distributions with multiple defect structures. This observation challenges the role of the nanoparticle precursor as a seed for certain syntheses and suggests the possibility of alternate nucleation pathways. Herein, we report a method to probe the role of the nanoparticle precursor in anisotropic nanoparticle nucleation with compositional and structural 'labels' to track their fate. We use the synthesis of gold triangular nanoprisms (Au TPs) as a model system. We propose a mechanism in which, rather than acting as a template, the nanoparticle precursor catalyzes homogenous nucleation of Au TPs.

  10. Nanoparticle Lasing Spasers

    NASA Astrophysics Data System (ADS)

    Odom, Teri

    Plasmon nanolasers, or spasers (surface plasmon amplification by stimulated emission of radiation) are devices based on plasmonic cavities and gain media that can compensate loss and achieve amplification of nano-localized electromagnetic fields. Several nanocavity architectures have been reported for spasers, such as a metal film-dielectric spacer-semiconductor nanowire configuration or arrays of plasmonic cavities, where the unit cells are nanoparticles or nanoholes. We will discuss two platforms based on nanoparticle arrays that support lattice plasmons for far-field directional emission that can achieve tunable lasing at room temperature. Also, we will describe competing and unique loss mechanisms in nanoparticle cavity arrays as well as the design principles for an optimized unidirectional lasing device by examining different plasmonic materials, unit cell shapes, and gain materials.

  11. Superbackscattering nanoparticle dimers.

    PubMed

    Liberal, Iñigo; Ederra, Iñigo; Gonzalo, Ramón; Ziolkowski, Richard W

    2015-07-10

    The theory and design of superbackscattering nanoparticle dimers are presented. We analytically derive the optimal configurations and the upper bound of their backscattering cross-sections. In particular, it is demonstrated that electrically small nanoparticle dimers can enhance the backscattering by a factor of 6.25 with respect to single dipolar particles. We demonstrate that optimal designs approaching this theoretical limit can be found by using a simple circuit model. The study of practical implementations based on plasmonic and high-permittivity particles has been also addressed. Moreover, the numerical examples reveal that the dimers can attain close to a fourfold enhancement of the single nanoparticle response even in the presence of high losses.

  12. The Smart Targeting of Nanoparticles

    PubMed Central

    Friedman, Adam D.; Claypool, Sarah E.; Liu, Rihe

    2014-01-01

    One major challenge in nanomedicine is how to selectively deliver nanoparticles to diseased tissues. Nanoparticle delivery system requires targeting for specific delivery to pathogenic sites when enhanced permeability and retention (EPR) is not suitable or inefficient. Functionalizing nanoparticles is a widely-used technique that allows for conjugation with targeting ligands, which possess inherent ability to direct selective binding to cell types or states and, therefore, confer “smartness” to nanoparticles. This review illustrates methods of ligand-nanoparticle functionalization, provides a cross-section of various ligand classes, including small molecules, peptides, antibodies, engineered proteins, or nucleic acid aptamers, and discusses some unconventional approaches currently under investigation. PMID:23470005

  13. Nanoparticles from renewable polymers

    PubMed Central

    Wurm, Frederik R.; Weiss, Clemens K.

    2014-01-01

    The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications. PMID:25101259

  14. Magnetophoresis of nanoparticles.

    PubMed

    Lim, Jitkang; Lanni, Caitlin; Evarts, Eric R; Lanni, Frederick; Tilton, Robert D; Majetich, Sara A

    2011-01-25

    Iron oxide cores of 35 nm are coated with gold nanoparticles so that individual particle motion can be tracked in real time through the plasmonic response using dark field optical microscopy. Although Brownian and viscous drag forces are pronounced for nanoparticles, we show that magnetic manipulation is possible using large magnetic field gradients. The trajectories are analyzed to separate contributions from the different types of forces. With field gradients up to 3000 T/m, forces as small as 1.5 fN are detected.

  15. Virus templated metallic nanoparticles.

    PubMed

    Aljabali, Alaa A A; Barclay, J Elaine; Lomonossoff, George P; Evans, David J

    2010-12-01

    Plant viruses are considered as nanobuilding blocks that can be used as synthons or templates for novel materials. Cowpea mosaic virus (CPMV) particles have been shown to template the fabrication of metallic nanoparticles by an electroless deposition metallization process. Palladium ions were electrostatically bound to the virus capsid and, when reduced, acted as nucleation sites for the subsequent metal deposition from solution. The method, although simple, produced highly monodisperse metallic nanoparticles with a diameter of ca. ≤35 nm. CPMV-templated particles were prepared with cobalt, nickel, iron, platinum, cobalt-platinum and nickel-iron.

  16. Nanoparticle shuttle memory

    DOEpatents

    Zettl, Alex Karlwalter [Kensington, CA

    2012-03-06

    A device for storing data using nanoparticle shuttle memory having a nanotube. The nanotube has a first end and a second end. A first electrode is electrically connected to the first end of the nanotube. A second electrode is electrically connected to the second end of the nanotube. The nanotube has an enclosed nanoparticle shuttle. A switched voltage source is electrically connected to the first electrode and the second electrode, whereby a voltage may be controllably applied across the nanotube. A resistance meter is also connected to the first electrode and the second electrode, whereby the electrical resistance across the nanotube can be determined.

  17. Nanoparticles from renewable polymers.

    PubMed

    Wurm, Frederik R; Weiss, Clemens K

    2014-01-01

    The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications.

  18. Nanoparticles: pharmacological and toxicological significance

    PubMed Central

    Medina, C; Santos-Martinez, M J; Radomski, A; Corrigan, O I; Radomski, M W

    2007-01-01

    Nanoparticles are tiny materials (<1000 nm in size) that have specific physicochemical properties different to bulk materials of the same composition and such properties make them very attractive for commercial and medical development. However, nanoparticles can act on living cells at the nanolevel resulting not only in biologically desirable, but also in undesirable effects. In contrast to many efforts aimed at exploiting desirable properties of nanoparticles for medicine, there are limited attempts to evaluate potentially undesirable effects of these particles when administered intentionally for medical purposes. Therefore, there is a pressing need for careful consideration of benefits and side effects of the use of nanoparticles in medicine. This review article aims at providing a balanced update of these exciting pharmacological and potentially toxicological developments. The classes of nanoparticles, the current status of nanoparticle use in pharmacology and therapeutics, the demonstrated and potential toxicity of nanoparticles will be discussed. PMID:17245366

  19. Chemical Aspects of Nanoparticle Ecotoxicology.

    PubMed

    Sigg, Laura; Behra, Renata; Groh, Ksenia; Isaacson, Carl; Odzak, Niksa; Piccapietra, Flavio; Röhder, Lena; Schug, Hannah; Yue, Yang; Schirmer, Kristin

    2014-11-01

    Nanoecotoxicology strives to understand the processes and mechanisms by which engineered nanoparticles (ENP) may exert toxic effects on aquatic organisms. Detailed knowledge of the chemical reactions of nanoparticles in the media and of their interactions with organisms is required to understand these effects. The processes of agglomeration of nanoparticles, of dissolution and release of toxic metal ions, and of production of reactive oxygen species (ROS) are considered in this article. Important questions concern the role of uptake of nanoparticles in various organisms, in contrast to uptake of ions released from nanoparticles and to nanoparticle attachment to organism surfaces. These interactions are illustrated for effects of silver nanoparticles (AgNP), cerium oxide (CeO2 NP) and titanium dioxide (TiO2 NP), on aquatic organisms, including algae, biofilms, fish cells and fish embryos.

  20. Thermally stable nanoparticles on supports

    DOEpatents

    Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

    2012-11-13

    An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

  1. Book Review: The future of spacetime. Stephen William Hawking (ed.); Kip S. Thorne, Igor Novikov, Timothy Ferris, Alan Lightman, and Richard Price, W.W. Norton & Company, 2002, 224 pp., US 25.95, ISBN 0393020223

    NASA Astrophysics Data System (ADS)

    Smeenk, Chris

    2003-12-01

    The study of Einstein's theory of general relativity experienced a renaissance beginning in the early 1960s. Prior to this resurgence of interest, general relativity was isolated from mainstream physics-admired for its elegance, perhaps, but only from a distance. The generation of students who risked their careers by entering this neglected field has now reached the age of festschrifts. In June of 2000, Caltech hosted ;Kipfest,; a conference in honor of Kip Thorne's 60th birthday. Thorne started graduate school at Princeton in 1962 and began research in general relativity under John Wheeler's guidance in the heady early days of the renaissance. Since then, he has played a prominent role in general relativity: as co-author of the influential textbook Gravitation, as a leader in research regarding astrophysical applications of Einstein's theory, and as a co-founder and chief advocate for the Laser Interferometer Gravitational Wave Observatory (LIGO), to mention a few aspects of his far-reaching work. ;Kipfest; included 14 speakers discussing fields to which Thorne has contributed. But the conference also reflected Thorne's long-standing commitment to communicating science to a general audience: Igor Novikov, Stephen Hawking, Timothy Ferris, and Alan Lightman gave popular talks at ;Kipfest,; with Thorne himself tricked into delivering a fifth. The Future of Spacetime gathers adaptations of these five lectures, along with a lengthy introductory essay by Richard Price.

  2. Nanoparticle-Based Biosensors and Bioassays

    SciTech Connect

    Liu, Guodong; Wang, Jun; Lin, Yuehe; Wang, Joseph

    2007-10-11

    In this book chapter, we review the recent advances in nanoparticles based bioassay. The nanoparticles include quantum dots, silica nanoparticles and apoferritin nanoparticles. The new nanoparticles-based labels hold great promise for multiplex protein and DNA detection and for enhancing the sensitivity of other bioassays.

  3. Asymmetric Hybrid Nanoparticles

    SciTech Connect

    Chumanov, George

    2015-11-05

    Hybrid Nanoparticles (AHNs) are rationally-designed multifunctional nanostructures and novel building blocks for the next generation of advanced materials and devices. Nanoscale materials attract considerable interest because of their unusual properties and potential for practical applications. Most of the activity in this field is focused on the synthesis of homogeneous nanoparticles from metals, metal oxides, semiconductors, and polymers. It is well recognized that properties of nanoparticles can be further enhanced if they are made as hybrid structures. This program is concerned with the synthesis, characterization, and application of such hybrid structures termed AHNs. AHNs are composed of a homogeneous core and several caps of different materials deposited on its surface (Fig. 1). Combined properties of the core and the caps as well as new properties that arise from core-cap and cap-cap interactions render AHNs multifunctional. In addition, specific chemical reactivity of the caps enables directional self-assembly of AHNs into complex architectures that are not possible with only spherical nanoparticles.

  4. Molecularly Imprinted Biodegradable Nanoparticles.

    PubMed

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-10

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  5. Nanoparticles in forensic science

    NASA Astrophysics Data System (ADS)

    Cantu, Antonio A.

    2008-10-01

    Nanoparticles appear in several areas of forensic science including security documents, paints, inks, and reagents that develop latent prints. One reagent (known as the silver physical developer) that visualizes the water insoluble components of latent print residue is based on the formation of highly charged silver nanoparticles. These attach to and grow on the residue and generate a silver image. Another such reagent involves highly charged gold nanoparticles. These attach to the residue forming a weak gold image which can be amplified with a silver physical developer. Nanoparaticles are also used in items such as paints, printing inks, and writing inks. Paints and most printing inks consist of nano-sized pigments in a vehicle. However, certain modern ink jet printing inks now contain nano-sized pigments to improve their light fastness and most gel inks are also based on nano scale pigments. These nanoparticlecontaining materials often appear as evidence and are thus subject to forensic characterization. Both luminescent (quantum dots), up-converting nano scale phosphors, and non luminescent nanoparticles are used as security tags to label product, add security to documents, and as anti counterfeiting measures. These assist in determining if an item is fraudulently made.

  6. Nanoparticles as biochemical sensors

    PubMed Central

    El-Ansary, Afaf; Faddah, Layla M

    2010-01-01

    There is little doubt that nanoparticles offer real and new opportunities in many fields, such as biomedicine and materials science. Such particles are small enough to enter almost all areas of the body, including cells and organelles, potentially leading to new approaches in nanomedicine. Sensors for small molecules of biochemical interest are of critical importance. This review is an attempt to trace the use of nanomaterials in biochemical sensor design. The possibility of using nanoparticles functionalized with antibodies as markers for proteins will be elucidated. Moreover, capabilities and applications for nanoparticles based on gold, silver, magnetic, and semiconductor materials (quantum dots), used in optical (absorbance, luminescence, surface enhanced Raman spectroscopy, surface plasmon resonance), electrochemical, and mass-sensitive sensors will be highlighted. The unique ability of nanosensors to improve the analysis of biochemical fluids is discussed either through considering the use of nanoparticles for in vitro molecular diagnosis, or in the biological/biochemical analysis for in vivo interaction with the human body. PMID:24198472

  7. Nanoparticle patterning for biomedicine

    PubMed Central

    Moghimi, Seyed Moein

    2016-01-01

    Summary Nanoparticles are being used for construction of complex and higher-order functional structures and metamaterials with applications in nanophotonics, information storage and biomedicine, to name a few. These innovations are briefly discussed within the context of future diagnostic and nanomedicine platform technologies and their possible self-assembly in vivo. PMID:28265533

  8. Nanoparticle patterning for biomedicine.

    PubMed

    Moghimi, Seyed Moein

    2016-01-01

    Nanoparticles are being used for construction of complex and higher-order functional structures and metamaterials with applications in nanophotonics, information storage and biomedicine, to name a few. These innovations are briefly discussed within the context of future diagnostic and nanomedicine platform technologies and their possible self-assembly in vivo.

  9. Toxicity of nanoparticles.

    PubMed

    Zoroddu, Maria Antonietta; Medici, Serenella; Ledda, Alessia; Nurchi, Valeria Marina; Lachowicz, Joanna I; Peana, Massimiliano

    2014-01-01

    Nowadays more than thousands of different nanoparticles are known, though no well-defined guidelines to evaluate their potential toxicity and to control their exposure are fully provided. The way of entry of nanoparticles together with their specificities such as chemistry, chemical composition, size, shape or morphology, surface charge and area can influence their biological activities and effects. A specific property may give rise to either a safe particle or to a dangerous one. The small size allows nanoparticles to enter the body by crossing several barriers, to pass into the blood stream and lymphatic system from where they can reach organs and tissues and strictly interact with biological structures, thus damaging their normal functions in different ways. This review provides a summary of what is known on the toxicology related to the specificity of nanoparticles, both as technological tools or ambient pollutants. The aim is to highlight their potential hazard and to provide a balanced update on all the important questions and directions that should be focused in the near future.

  10. Molecularly Imprinted Biodegradable Nanoparticles

    NASA Astrophysics Data System (ADS)

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization.

  11. Molecularly Imprinted Biodegradable Nanoparticles

    PubMed Central

    Gagliardi, Mariacristina; Bertero, Alice; Bifone, Angelo

    2017-01-01

    Biodegradable polymer nanoparticles are promising carriers for targeted drug delivery in nanomedicine applications. Molecu- lar imprinting is a potential strategy to target polymer nanoparticles through binding of endogenous ligands that may promote recognition and active transport into specific cells and tissues. However, the lock-and-key mechanism of molecular imprinting requires relatively rigid cross-linked structures, unlike those of many biodegradable polymers. To date, no fully biodegradable molecularly imprinted particles have been reported in the literature. This paper reports the synthesis of a novel molecularly- imprinted nanocarrier, based on poly(lactide-co-glycolide) (PLGA) and acrylic acid, that combines biodegradability and molec- ular recognition properties. A novel three-arm biodegradable cross-linker was synthesized by ring-opening polymerization of glycolide and lactide initiated by glycerol. The resulting macromer was functionalized by introduction of end-functions through reaction with acryloyl chloride. Macromer and acrylic acid were used for the synthesis of narrowly-dispersed nanoparticles by radical polymerization in diluted conditions in the presence of biotin as template molecule. The binding capacity of the imprinted nanoparticles towards biotin and biotinylated bovine serum albumin was twentyfold that of non-imprinted nanoparti- cles. Degradation rates and functional performances were assessed in in vitro tests and cell cultures, demonstrating effective biotin-mediated cell internalization. PMID:28071745

  12. Starch nanoparticles: a review.

    PubMed

    Le Corre, Déborah; Bras, Julien; Dufresne, Alain

    2010-05-10

    Starch is a natural, renewable, and biodegradable polymer produced by many plants as a source of stored energy. It is the second most abundant biomass material in nature. The starch structure has been under research for years, and because of its complexity, an universally accepted model is still lacking (Buleon, A.; et al. Int. J. Biol. Macromol. 1998, 23, 85-112). However, the predominant model for starch is a concentric semicrystalline multiscale structure that allows the production of new nanoelements: (i) starch nanocrystals resulting from the disruption of amorphous domains from semicrystalline granules by acid hydrolysis and (ii) starch nanoparticles produced from gelatinized starch. This paper intends to give a clear overview of starch nanoparticle preparation, characterization, properties, and applications. Recent studies have shown that they could be used as fillers to improve mechanical and barrier properties of biocomposites. Their use for industrial packaging, continuously looking for innovative solutions for efficient and sustainable systems, is being investigated. Therefore, recently, starch nanoparticles have been the focus of an exponentially increasing number of works devoted to develop biocomposites by blending starch nanoparticles with different biopolymeric matrices. To our knowledge, this topic has never been reviewed, despite several published strategies and conclusions.

  13. Nanoparticle Based Logic Gates

    NASA Astrophysics Data System (ADS)

    Berven, Christopher; Wybourne, Martin; Longstreth, Lydia

    2003-05-01

    Ligand stabilized gold nanoparticles have novel properties that can be exploited for their use as possible building blocks for room-temperature single electron devices. With a core of 70 gold atoms or less (diameter <= 1.4 nm), the self-capacitance of these particles is a fraction of an atto-Farad. This small capacitance translates into an electrostatic charging energy well in excess of the thermal energy at room temperature. Single electron behavior has been demonstrated in one- and two-dimensional arrays of nanoparticles. In traditional single electron devices, the self-capacitance is negligible, whereas the self-capacitance in nanoparticle based devices can be the dominant capacitance. This means that the effect of charging a nanoparticle chain is highly localized which is in contrast to traditional single electron devices where the induced potential due to an excess electron on an island is felt by many neighboring islands. As a result, the current-voltage characteristics and plots of stable electron occupancy in the arrays have different behavior to that found in traditional devices. We show that this new regime of tunneling behavior can be exploited to create a novel family of single-electron logic gate devices. Using numerical simulation we have found that when a one-dimensional array of nanoparticles is gated in an electron-pump arrangement and properly biased, the behavior is that of an AND gate. The addition of an inverter circuit results in NAND gate behavior, the inverter providing the power necessary for the cascading of multiple NAND gates and the generation of arbitrary logic circuits.

  14. DNA templated magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph M.

    Recent discoveries in nanoscience are predicted to potentially revolutionize future technologies in an extensive number of fields. These developments are contingent upon discovering new and often unconventional methods to synthesize and control nanoscale components. Nature provides several examples of working nanotechnology such as the use of programmed self assembly to build and deconstruct complex molecular systems. We have adopted a method to control the one dimensional assembly of magnetic nanoparticles using DNA as a scaffold molecule. With this method we have demonstrated the ability to organize 5 nm particles into chains that stretch up to ˜20 mum in length. One advantage of using DNA compared is the ability of the molecule to interact with other biomolecules. After assembling particles onto DNA we have been able to cleave the molecule into smaller fragments using restriction enzymes. Using ligase enzymes we have re-connected these fragments, coated with either gold or iron oxide, to form long one-dimensional arrangements of the two different types of nanoparticles on a single molecular guide. We have also created a sensitive magnetic field sensor by incorporating magnetic nanoparticle coated DNA strands with microfabricated electrodes. The IV characteristics of the aligned nanoparticles are dependant on the magnitude of an externally applied magnetic field. This transport phenomenon known as tunneling magnetoresistance (TMR) shows room temperature resistance of our devices over 80% for cobalt ferrite coated DNA when a field of 20 kOe is applied. In comparison, studies using two dimensional nanoparticle films of irox oxides xii only exhibit a 35% MR effect. Confinement into one dimension using the DNA guide produces a TMR mechanism which produces significant increases in magnetoresistance. This property can be utilized for applications in magnetic field sensing, data storage, and logic elements.

  15. Progress toward clonable inorganic nanoparticles

    NASA Astrophysics Data System (ADS)

    Ni, Thomas W.; Staicu, Lucian C.; Nemeth, Richard S.; Schwartz, Cindi L.; Crawford, David; Seligman, Jeffrey D.; Hunter, William J.; Pilon-Smits, Elizabeth A. H.; Ackerson, Christopher J.

    2015-10-01

    Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular electron tomography shows the nanoparticles as intracellular, of narrow dispersity, symmetrically irregular and without any observable membrane or structured protein shell. Protein mass spectrometry of a fractionated soluble cytosolic material with selenite reducing capability identified nitrite reductase and glutathione reductase homologues as NADPH dependent candidate enzymes for the reduction of selenite to zerovalent Se nanoparticles. In vitro experiments with commercially sourced glutathione reductase revealed that the enzyme can reduce SeO32- (selenite) to Se nanoparticles in an NADPH-dependent process. The disappearance of the enzyme as determined by protein assay during nanoparticle formation suggests that glutathione reductase is associated with or possibly entombed in the nanoparticles whose formation it catalyzes. Chemically dissolving the nanoparticles releases the enzyme. The size of the nanoparticles varies with SeO32- concentration, varying in size form 5 nm diameter when formed at 1.0 μM [SeO32-] to 50 nm maximum diameter when formed at 100 μM [SeO32-]. In aggregate, we suggest that glutathione reductase possesses the key attributes of a clonable nanoparticle system: ion reduction, nanoparticle retention and size control of the nanoparticle at the enzyme site.Pseudomonas moraviensis stanleyae was recently isolated from the roots of the selenium (Se) hyperaccumulator plant Stanleya pinnata. This bacterium tolerates normally lethal concentrations of SeO32- in liquid culture, where it also produces Se nanoparticles. Structure and cellular ultrastructure of the Se nanoparticles as determined by cellular

  16. Magnetoacoustic Sensing of Magnetic Nanoparticles.

    PubMed

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-11

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.

  17. Magnetoacoustic Sensing of Magnetic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Rosenthal, Amir; Myklatun, Ahne; Westmeyer, Gil G.; Sergiadis, George; Ntziachristos, Vasilis

    2016-03-01

    The interaction of magnetic nanoparticles and electromagnetic fields can be determined through electrical signal induction in coils due to magnetization. However, the direct measurement of instant electromagnetic energy absorption by magnetic nanoparticles, as it relates to particle characterization or magnetic hyperthermia studies, has not been possible so far. We introduce the theory of magnetoacoustics, predicting the existence of second harmonic pressure waves from magnetic nanoparticles due to energy absorption from continuously modulated alternating magnetic fields. We then describe the first magnetoacoustic system reported, based on a fiber-interferometer pressure detector, necessary for avoiding electric interference. The magnetoacoustic system confirmed the existence of previously unobserved second harmonic magnetoacoustic responses from solids, magnetic nanoparticles, and nanoparticle-loaded cells, exposed to continuous wave magnetic fields at different frequencies. We discuss how magnetoacoustic signals can be employed as a nanoparticle or magnetic field sensor for biomedical and environmental applications.

  18. Study of iron nanoparticle melting

    NASA Astrophysics Data System (ADS)

    Fedorov, A. V.; Shulgin, A. V.; Lavruk, S. A.

    2016-10-01

    In paper melting process of iron nanoparticles was investigated with molecular dynamics method. Melting temperatures was found for particles with radius from 1.5 to 4 nm. Results match with data of other authors. Heat capacity was calculated based on investigation of caloric curves. Dependence between heat capacity and temperature for different size of nanoparticles was approximated. Heat conductivity of iron nanoparticles was calculated.

  19. Adsorption isotherms of charged nanoparticles.

    PubMed

    Dos Santos, Alexandre P; Bakhshandeh, Amin; Diehl, Alexandre; Levin, Yan

    2016-10-19

    We present theory and simulations which allow us to quantitatively calculate the amount of surface adsorption excess of charged nanoparticles onto a charged surface. The theory is very accurate for weakly charged nanoparticles and can be used at physiological concentrations of salt. We have also developed an efficient simulation algorithm which can be used for dilute suspensions of nanoparticles of any charge, even at very large salt concentrations. With the help of the new simulation method, we are able to efficiently calculate the adsorption isotherms of highly charged nanoparticles in suspensions containing multivalent ions, for which there are no accurate theoretical methods available.

  20. Silver Nanoparticles in Dental Biomaterials

    PubMed Central

    Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

    2015-01-01

    Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

  1. Magnetic Nanoparticle Sensors

    PubMed Central

    Koh, Isaac; Josephson, Lee

    2009-01-01

    Many types of biosensors employ magnetic nanoparticles (diameter = 5–300 nm) or magnetic particles (diameter = 300–5,000 nm) which have been surface functionalized to recognize specific molecular targets. Here we cover three types of biosensors that employ different biosensing principles, magnetic materials, and instrumentation. The first type consists of magnetic relaxation switch assay-sensors, which are based on the effects magnetic particles exert on water proton relaxation rates. The second type consists of magnetic particle relaxation sensors, which determine the relaxation of the magnetic moment within the magnetic particle. The third type is magnetoresistive sensors, which detect the presence of magnetic particles on the surface of electronic devices that are sensitive to changes in magnetic fields on their surface. Recent improvements in the design of magnetic nanoparticles (and magnetic particles), together with improvements in instrumentation, suggest that magnetic material-based biosensors may become widely used in the future. PMID:22408498

  2. Hydrogel nanoparticle based immunoassay

    DOEpatents

    Liotta, Lance A; Luchini, Alessandra; Petricoin, Emanuel F; Espina, Virginia

    2015-04-21

    An immunoassay device incorporating porous polymeric capture nanoparticles within either the sample collection vessel or pre-impregnated into a porous substratum within fluid flow path of the analytical device is presented. This incorporation of capture particles within the immunoassay device improves sensitivity while removing the requirement for pre-processing of samples prior to loading the immunoassay device. A preferred embodiment is coreshell bait containing capture nanoparticles which perform three functions in one step, in solution: a) molecular size sieving, b) target analyte sequestration and concentration, and c) protection from degradation. The polymeric matrix of the capture particles may be made of co-polymeric materials having a structural monomer and an affinity monomer, the affinity monomer having properties that attract the analyte to the capture particle. This device is useful for point of care diagnostic assays for biomedical applications and as field deployable assays for environmental, pathogen and chemical or biological threat identification.

  3. Metallic nanoparticles meet metadynamics.

    PubMed

    Pavan, L; Rossi, K; Baletto, F

    2015-11-14

    Metadynamics coupled with classical molecular dynamics has been successfully applied to sample the configuration space of metallic and bimetallic nanoclusters. We implement a new set of collective variables related to the pair distance distribution function of the nanoparticle to achieve an exhaustive isomer sampling. As paradigmatic examples, we apply our methodology to Ag147, Pt147, and their alloy Ag(shell)Pt(core) at 2:1 and 1:1 chemical compositions. The proposed scheme is able to reproduce the known solid-solid structural transformation pathways, based on the Lipscomb's diamond-square-diamond mechanisms, both in mono and bimetallic nanoparticles. A discussion of the free energy barriers involved in these processes is provided.

  4. Metallic nanoparticles meet metadynamics

    NASA Astrophysics Data System (ADS)

    Pavan, L.; Rossi, K.; Baletto, F.

    2015-11-01

    Metadynamics coupled with classical molecular dynamics has been successfully applied to sample the configuration space of metallic and bimetallic nanoclusters. We implement a new set of collective variables related to the pair distance distribution function of the nanoparticle to achieve an exhaustive isomer sampling. As paradigmatic examples, we apply our methodology to Ag147, Pt147, and their alloy AgshellPtcore at 2:1 and 1:1 chemical compositions. The proposed scheme is able to reproduce the known solid-solid structural transformation pathways, based on the Lipscomb's diamond-square-diamond mechanisms, both in mono and bimetallic nanoparticles. A discussion of the free energy barriers involved in these processes is provided.

  5. Nanoparticles and Ocean Optics

    DTIC Science & Technology

    2008-09-30

    Nanoparticles and Ocean Optics William M. Balch Bigelow Laboratory for Ocean Sciences, POB 475, W. Boothbay Harbor, ME...Laboratory for Ocean Sciences, POB 475, W. Boothbay Harbor, ME 04575 phone: (207) 633-9600 fax: (207) 633-9641 email: jgoes@bigelow.org Award Number...characterization of virus/host assemblages for use in lab -based dilution experiments. We tested methods for the separation of naturally occurring virus and host

  6. Nanoparticles and Ocean Optics

    DTIC Science & Technology

    2007-09-30

    Nanoparticles and Ocean Optics William M. Balch Bigelow Laboratory for Ocean Sciences, POB 475 W. Boothbay Harbor, ME 04575 phone: (207) 633...Ocean Sciences, POB 475 W. Boothbay Harbor, ME 04575 phone: (207) 633-9600 fax: (207) 633-9641 email: jgoes@bigelow.org Award Number...and characterization of virus/host assemblages for use in lab -based dilution experiments. We tested methods for the separation of naturally occurring

  7. Nanoparticles and Ocean Optics

    DTIC Science & Technology

    2008-01-01

    Nanoparticles and Ocean Optics William M. Balch Bigelow Laboratory for Ocean Sciences, POB 475 W. Boothbay Harbor, ME 04575 phone: (207) 633...Ocean Sciences, POB 475 W. Boothbay Harbor, ME 04575 phone: (207) 633-9600 fax: (207) 633-9641 email: jgoes@bigelow.org Award Number...and characterization of virus/host assemblages for use in lab -based dilution experiments. We tested methods for the separation of naturally occurring

  8. Biotemplated magnetic nanoparticle arrays.

    PubMed

    Galloway, Johanna M; Bramble, Jonathan P; Rawlings, Andrea E; Burnell, Gavin; Evans, Stephen D; Staniland, Sarah S

    2012-01-23

    Immobilized biomineralizing protein Mms6 templates the formation of uniform magnetite nanoparticles in situ when selectively patterned onto a surface. Magnetic force microscopy shows that the stable magnetite particles maintain their magnetic orientation at room temperature, and may be exchange coupled. This precision-mixed biomimetic/soft-lithography methodology offers great potential for the future of nanodevice fabrication. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Nanoparticle Toxicity Mechanisms: Genotoxicity

    NASA Astrophysics Data System (ADS)

    Botta, Alain; Benameur, Laı̈la

    Despite the relatively small amount of convincing experimental data, the potentially genotoxic nature of certain nanoparticles seems plausible, owing in particular to the presence of reactive oxygen species (ROS) such as the superoxide anion O2 • - , the hydroxyl radical • OH, and singlet oxygen 1O2, and reactive nitrogen species (RNS) such as nitrogen monoxide NO, the peroxynitrite anion ONOO - , the peroxynitrite radical ONOO • , and dinitrogen trioxide N2O3, a powerful nitration agent.

  10. Characterization of starch nanoparticles

    NASA Astrophysics Data System (ADS)

    Szymońska, J.; Targosz-Korecka, M.; Krok, F.

    2009-01-01

    Nanomaterials already attract great interest because of their potential applications in technology, food science and medicine. Biomaterials are biodegradable and quite abundant in nature, so they are favoured over synthetic polymer based materials. Starch as a nontoxic, cheap and renewable raw material is particularly suitable for preparation of nanoparticles. In the paper, the structure and some physicochemical properties of potato and cassava starch particles of the size between 50 to 100 nm, obtained by mechanical treatment of native starch, were presented. We demonstrated, with the aim of the Scanning Electron Microscopy (SEM) and the non-contact Atomic Force Microscopy (nc-AFM), that the shape and dimensions of the obtained nanoparticles both potato and cassava starch fit the blocklets - previously proposed as basic structural features of native starch granules. This observation was supported by aqueous solubility and swelling power of the particles as well as their iodine binding capacity similar to those for amylopectin-type short branched polysaccharide species. Obtained results indicated that glycosidic bonds of the branch linkage points in the granule amorphous lamellae might be broken during the applied mechanical treatment. Thus the released amylopectin clusters could escape out of the granules. The starch nanoparticles, for their properties qualitatively different from those of native starch granules, could be utilized in new applications.

  11. Nanoparticle-polymer photovoltaic cells.

    PubMed

    Saunders, Brian R; Turner, Michael L

    2008-04-21

    The need to develop and deploy large-scale, cost-effective, renewable energy is becoming increasingly important. In recent years photovoltaic (PV) cells based on nanoparticles blended with semiconducting polymers have achieved good power conversion efficiencies (PCE). All the nanoparticle types used in these PV cells can be considered as colloids. These include spherical, rod-like or branched organic or inorganic nanoparticles. Nanoparticle-polymer PV cells have the long-term potential to provide low cost, high-efficiency renewable energy. The maximum PCE achieved to date is about 5.5%. This value should rise as recently reported theoretical predictions suggest 10% is achievable. However, there are a number of challenges that remain to be overcome. In this review two general types of nanoparticle-polymer PV cells are considered and compared in detail. The organic nanoparticle-polymer PV cells contain fullerene derivatives (e.g., phenyl C61-butyric acid methyl ester, PCBM) or single-walled nanotubes as the nanoparticle phase. The second type is hybrid inorganic nanoparticle-polymer PV cells. These contain semiconducting nanoparticles that include CdSe, ZnO or PbS. The structure-property relationships that apply to both the polymer and nanoparticle phases are considered. The principles underlying nanoparticle-polymer PV cell operation are also discussed. An outcome of consideration of the literature in both areas are two sets of assembly conditions that are suggested for constructing PCBM-P3HT (P3HT is poly(3-hexylthiophene)) or CdSe-P3HT PV cells with reasonable power conversion efficiency. The maximum PCE reported for organic nanoparticle PV cells is about twice that for inorganic nanoparticle-polymer PV cells. This appears to be related to morphological differences between the respective photoactive layers. The morphological differences are attributed to differences in the colloidal stability of the nanoparticle/polymer/solvent mixtures used to prepare the

  12. Thermal treatment of magnetite nanoparticles

    PubMed Central

    Wykowska, Urszula; Satula, Dariusz; Nordblad, Per

    2015-01-01

    Summary This paper presents the results of a thermal treatment process for magnetite nanoparticles in the temperature range of 50–500 °C. The tested magnetite nanoparticles were synthesized using three different methods that resulted in nanoparticles with different surface characteristics and crystallinity, which in turn, was reflected in their thermal durability. The particles were obtained by coprecipitation from Fe chlorides and decomposition of an Fe(acac)3 complex with and without a core–shell structure. Three types of ferrite nanoparticles were produced and their thermal stability properties were compared. In this study, two sets of unmodified magnetite nanoparticles were used where crystallinity was as determinant of the series. For the third type of particles, a Ag shell was added. By comparing the coated and uncoated particles, the influence of the metallic layer on the thermal stability of the nanoparticles was tested. Before and after heat treatment, the nanoparticles were examined using transmission electron microscopy, IR spectroscopy, differential scanning calorimetry, X-ray diffraction and Mössbauer spectroscopy. Based on the obtained results, it was observed that the fabrication methods determine, to some extent, the sensitivity of the nanoparticles to external factors. PMID:26199842

  13. Gluing Soft Interfaces by Nanoparticles

    NASA Astrophysics Data System (ADS)

    Cao, Zhen; Dobrynin, Andrey

    Using a combination of the molecular dynamics simulations and scaling analysis we studied reinforcement of interface between two soft gel-like materials by spherical nanoparticles. Analysis of the simulations shows that the depth of penetration of a nanoparticle into a gel is determined by a balance of the elastic energy of the gel and nanoparticle deformations and the surface energy of nanoparticle/gel interface. In order to evaluate work of adhesion of the reinforced interface, the potential of mean force for separation of two gels was calculated. These simulations showed that the gel separation proceeds through formation of necks connecting nanoparticle with two gels. The shapes of the necks are controlled by a fine interplay between nanoparticle/gel surface energies and elastic energy of the neck deformation. Our simulations showed that by introducing nanoparticles at soft interfaces, the work required for separation of two gels could be 10-100 times larger than the work of adhesion between two gels without nanoparticle reinforcement. These results provide insight in understanding the mechanism of gluing soft gels and biological tissues by nano- and micro-sized particles. NSF DMR-1409710.

  14. Synthesizing nanoparticles by mimicking nature

    EPA Science Inventory

    As particulate matter with at least one dimension that is less than 100 nm, nanoparticles are the minuscule building blocks of new commercial products and consumer materials in the emerging field of nanotechnology. Nanoparticles are being discovered and introduced in the marketpl...

  15. Synthesizing nanoparticles by mimicking nature

    EPA Science Inventory

    As particulate matter with at least one dimension that is less than 100 nm, nanoparticles are the minuscule building blocks of new commercial products and consumer materials in the emerging field of nanotechnology. Nanoparticles are being discovered and introduced in the marketpl...

  16. "Clickable" nanoparticles for targeted imaging.

    PubMed

    Sun, Eric Yi; Josephson, Lee; Weissleder, Ralph

    2006-01-01

    Nanomaterials functionalized with targeting ligands are increasingly recognized as useful materials for molecular imaging and drug delivery. Here we describe the development and validation of azide-alkyne reactions ("click chemistry") for the rapid, site-specific modification of nanoparticles with small molecules. The facile preparation of stable nanoparticles bearing azido or alkyne groups capable of reaction with their corresponding counterpart functionalized small molecules is demonstrated. The Cu(I)-catalyzed cycloaddition of azides and alkynes is shown to be a highly efficient and selective method for point functionalization of magnetic nanoparticles. Derivatized nanoparticles bearing biotin, fluorochrome, or steroid moieties are stable for several months. Nanoparticle click chemistry will be useful for other nanomaterials, design of novel sensors, and drug delivery vehicles.

  17. Compressibility of zinc sulfide nanoparticles

    SciTech Connect

    Gilbert, B.; Zhang, H.; Chen, B.; Banfield, J. F.; Kunz, M.; Huang, F.

    2006-09-15

    We describe a high-pressure x-ray diffraction (XRD) study of the compressibility of several samples of ZnS nanoparticles. The nanoparticles were synthesized with a range of sizes and surface chemical treatments in order to identify the factors that determine nanoparticle compressibility. Refinement of the XRD data revealed that all ZnS nanoparticles in the nominally cubic (sphalerite) phase exhibited a previously unobserved structural distortion under ambient conditions that exhibited, in addition, a dependence on pressure. Our results show that the compressibility of ZnS nanoparticles increases substantially as the particle size decreases, and we propose an interpretation based upon the available mechanisms of structural compliance in nanoscale vs bulk materials.

  18. Optical Properties of Copper Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kalenskii, A. V.; Zvekov, A. A.; Nikitin, A. P.; Anan'eva, M. V.

    2015-12-01

    Spectral dependences of the light extinction, absorption, and scattering efficiency factors of copper nanoparticles attendant to variations of their radii are calculated. A plasmon maximum is observed on the spectral dependence of the extinction efficiency factor for nanoparticle radii 10-60 nm. The maximum of the absorption efficiency factor is shifted toward red wavelengths with increasing radius of copper nanoparticles. Results are interpreted based on the special features of the spectral dependence of the complex copper refractive index. It is shown that the copper nanoparticles with radius of 35 nm placed into a transparent matrix with refractive index of 1.54 (secondary explosive pentaerythritol tetranitrate) possess a very high value of the absorption efficiency factor (2.9) of the second harmonic of a neodymium laser. Our investigations suggest that the copper nanoparticles are perspective material for application in compositions for optical detonator capsules.

  19. Responsive foams for nanoparticle delivery.

    PubMed

    Tang, Christina; Xiao, Edward; Sinko, Patrick J; Szekely, Zoltan; Prud'homme, Robert K

    2015-09-01

    We have developed responsive foam systems for nanoparticle delivery. The foams are easy to make, stable at room temperature, and can be engineered to break in response to temperature or moisture. Temperature-responsive foams are based on the phase transition of long chain alcohols and could be produced using medical grade nitrous oxide as a propellant. These temperature-sensitive foams could be used for polyacrylic acid (PAA)-based nanoparticle delivery. We also discuss moisture-responsive foams made with soap pump dispensers. Polyethylene glycol (PEG)-based nanoparticles or PMMA latex nanoparticles were loaded into Tween 20 foams and the particle size was not affected by the foam formulation or foam break. Using biocompatible detergents, we anticipate this will be a versatile and simple approach to producing foams for nanoparticle delivery with many potential pharmaceutical and personal care applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Laser printing single gold nanoparticles.

    PubMed

    Urban, Alexander S; Lutich, Andrey A; Stefani, Fenando D; Feldmann, Jochen

    2010-12-08

    Current colloidal synthesis is able to produce an extensive spectrum of nanoparticles with unique optoelectronic, magnetic, and catalytic properties. In order to exploit them in nanoscale devices, flexible methods are needed for the controlled integration of nanoparticles on surfaces with few-nanometer precision. Current technologies usually involve a combination of molecular self-assembly with surface patterning by diverse lithographic methods like UV, dip-pen, or microcontact printing.(1,2) Here we demonstrate the direct laser printing of individual colloidal nanoparticles by using optical forces for positioning and the van der Waals attraction for binding them to the substrate. As a proof-of-concept, we print single spherical gold nanoparticles with a positioning precision of 50 nm. By analyzing the printing mechanism, we identify the key physical parameters controlling the method, which has the potential for the production of nanoscale devices and circuits with distinct nanoparticles.

  1. Mesoporous silica templated zirconia nanoparticles

    NASA Astrophysics Data System (ADS)

    Ballem, Mohamed A.; Córdoba, José M.; Odén, Magnus

    2011-07-01

    Nanoparticles of zirconium oxide (ZrO2) were synthesized by infiltration of a zirconia precursor (ZrOCl2·8H2O) into a SBA-15 mesoporous silica mold using a wet-impregnation technique. X-ray diffractometry and high-resolution transmission electron microscopy show formation of stable ZrO2 nanoparticles inside the silica pores after a thermal treatment at 550 °C. Subsequent leaching out of the silica template by NaOH resulted in well-dispersed ZrO2 nanoparticles with an average diameter of 4 nm. The formed single crystal nanoparticles are faceted with 110 surfaces termination suggesting it to be the preferred growth orientation. A growth model of these nanoparticles is also suggested.

  2. Composite Nanoparticles for Gene Delivery

    PubMed Central

    Wang, Yuhua; Huang, Leaf

    2016-01-01

    Nanoparticle-mediated gene and siRNA delivery has been an appealing area to gene therapists when they attempt to treat the diseases by manipulating the genetic information in the target cells. However, the advances in materials science could not keep up with the demand for multifunctional nanomaterials to achieve desired delivery efficiency. Researchers have thus taken an alternative approach to incorporate various materials into single composite nanoparticle using different fabrication methods. This approach allows nanoparticles to possess defined nanostructures as well as multiple functionalities to overcome the critical extracellular and intracellular barriers to successful gene delivery. This chapter will highlight the advances of fabrication methods that have the most potential to translate nanoparticles from bench to bedside. Furthermore, a major class of composite nanoparticle–lipid-based composite nanoparticles will be classified based on the components and reviewed in details. PMID:25409605

  3. The ALAN Review. Volume 9, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1981-01-01

    The articles in this journal issue focus on adolescent literature. In the first article, author Sue Ellen Bridgers explains how she writes books, while the second article offers an analysis of the recent works of Paul Zindel. The third article presents a discussion of the treatment of outsiders, such as the mentally ill, in four Roy Brown…

  4. The ALAN Review. Volume 9, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1981-01-01

    The articles in this journal issue focus on adolescent literature. In the first article, author Sue Ellen Bridgers explains how she writes books, while the second article offers an analysis of the recent works of Paul Zindel. The third article presents a discussion of the treatment of outsiders, such as the mentally ill, in four Roy Brown…

  5. The ALAN Review. Volume 8, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1980-01-01

    The articles in this journal issue focus on adolescent literature. Topics covered in the articles include: (1) teaching adolescent literature about minorities to majority group students, (2) death in adolescent literature, (3) trends in German youth literature, and (4) female identity in the young adult novel. In addition, the journal issue…

  6. The ALAN Review. Volume 8, No. 1.

    ERIC Educational Resources Information Center

    Ellis, W. Geiger, Ed.; Ward, Dan, Ed.

    1980-01-01

    The articles in this journal issue focus on adolescent literature. Topics covered in the articles include: (1) teaching adolescent literature about minorities to majority group students, (2) death in adolescent literature, (3) trends in German youth literature, and (4) female identity in the young adult novel. In addition, the journal issue…

  7. Host thin films incorporating nanoparticles

    NASA Astrophysics Data System (ADS)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  8. Antibacterial effects of laser ablated Ni nanoparticles

    NASA Astrophysics Data System (ADS)

    Shamaila, S.; Wali, H.; Sharif, R.; Nazir, J.; Zafar, N.; Rafique, M. S.

    2013-10-01

    The interaction of nickel nanoparticles with Escherichia coli (E. coli) bacteria has been studied. The nickel nanoparticles have been fabricated by continuous wave laser ablation of nickel target and their properties are studied using different characterization techniques. The antibacterial activity of nickel nanoparticles was checked against E. coli bacteria. Escherichia coli were cultured in nutrients broth and different concentrations of nickel nanoparticles were added to bacterial culture solution to investigate the interaction of nickel nanoparticles with bacteria and to check toxicity of the nickel nanoparticles against E. coli. The fabricated Ni nanoparticles have exhibited considerable antimicrobial activity against E. coli.

  9. ATMP-stabilized iron nanoparticles: chelator-controlled nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Greenlee, Lauren F.; Rentz, Nikki S.

    2014-11-01

    In this study, we characterize iron nanoparticles synthesized in water in the presence of a phosphonate chelator, amino tris(methylene phosphonic acid) (ATMP) for a range of molar ratios of ATMP to iron. An increase in the molar ratio from 0.05 to 0.8 decreases nanoparticle size from approximately 150 nm to less than 10 nm. Zeta potential measurements were used to evaluate colloidal stability. Zeta potential values varied as a function of pH, and zeta potential values decreased with increasing pH. At lower molar ratios of ATMP to iron, the zeta potential varied between 15 and -40 mV, passing through an isoelectric point at pH 7.5. At higher ratios, the zeta potential was negative across the measured pH range of 2-12 and varied from -2 to -55 mV. Diffraction analysis indicates that ATMP-stabilized iron nanoparticles may have a nano-crystalline structure, potentially with regions of amorphous iron. Characterization results of ATMP-stabilized iron nanoparticles are compared to results obtained for carboxymethyl cellulose (CMC)-stabilized iron nanoparticles. CMC stabilization caused similar peak broadening in diffraction spectra as for ATMP, suggesting similar nano-crystalline/amorphous structure; however, an increase in the molar ratio of CMC to iron did not cause the same reduction in nanoparticle size as was observed for ATMP-stabilized iron nanoparticles.

  10. Mucus permeating thiomer nanoparticles.

    PubMed

    Köllner, S; Dünnhaupt, S; Waldner, C; Hauptstein, S; Pereira de Sousa, I; Bernkop-Schnürch, A

    2015-11-01

    The aim of this study was to develop and evaluate a novel mucoadhesive drug delivery system based on thiolated poly(acrylic acid) nanoparticles exhibiting mucolytic properties to enhance particle diffusion into deeper mucus regions before adhesion. Mediated by a carbodiimide, cysteine and the mucolytic enzyme papain were covalently attached to poly(acrylic acid) via amide bond formation. The conjugates were co-precipitated with calcium chloride in order to obtain papain modified (PAA-pap) and thiolated nanoparticles (PAA-cys) as well as particles containing both conjugates (PAA-cys-pap). The nanoparticulate systems were characterized regarding particle size distribution and zeta potential. Particle transport was investigated by diffusion studies across intestinal mucus using two different techniques. Furthermore, mucoadhesive properties of all particles were evaluated via rheological measurements. Results demonstrated that all nanoparticles were in a size range of 158-214 nm and showed negative zeta potentials. Due to the presence of papain, the PAA-cys-pap particles were capable of cleaving mucoglycoprotein substructures and consequently exhibited a 2.0-fold higher penetration into the mucus layer in comparison with PAA-cys particles. Within the rheological studies, an 1.9-fold increase in mucoadhesion could be achieved for the nanoparticulate system based on thiolated PAA compared to papain modified particles (PAA-pap). Therefore, the newly developed particulate system (PAA-cys-pap) is characterized by mucoadhesive as well as mucolytic properties. The combination of both effects - mucus-permeating and mucoadhesive properties - might be a promising strategy for the development of oral drug delivery systems to overcome the mucus barrier and providing a prolonged residence time close to the absorption membrane. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Antibacterial properties of nanoparticles.

    PubMed

    Hajipour, Mohammad J; Fromm, Katharina M; Ashkarran, Ali Akbar; Jimenez de Aberasturi, Dorleta; de Larramendi, Idoia Ruiz; Rojo, Teofilo; Serpooshan, Vahid; Parak, Wolfgang J; Mahmoudi, Morteza

    2012-10-01

    Antibacterial agents are very important in the textile industry, water disinfection, medicine, and food packaging. Organic compounds used for disinfection have some disadvantages, including toxicity to the human body, therefore, the interest in inorganic disinfectants such as metal oxide nanoparticles (NPs) is increasing. This review focuses on the properties and applications of inorganic nanostructured materials and their surface modifications, with good antimicrobial activity. Such improved antibacterial agents locally destroy bacteria, without being toxic to the surrounding tissue. We also provide an overview of opportunities and risks of using NPs as antibacterial agents. In particular, we discuss the role of different NP materials.

  12. Triggered Nanoparticles as Therapeutics

    PubMed Central

    Kim, Chang Soo; Duncan, Bradley; Creran, Brian; Rotello, Vincent M.

    2013-01-01

    Summary Drug delivery systems (DDSs) face several challenges including site-specific delivery, stability, and the programmed release of drugs. Engineered nanoparticle (NP) surfaces with responsive moieties can enhance the efficacy of DDSs for in vitro and in vivo systems. This triggering process can be achieved through both endogenous (biologically controlled release) and exogenous (external stimuli controlled release) activation. In this review, we will highlight recent examples of the use of triggered release strategies of engineered nanomaterials for in vitro and in vivo applications. PMID:24159362

  13. Optical manipulation by nonlinear response of nanoparticles

    NASA Astrophysics Data System (ADS)

    Ishihara, Hajime; Nakai, Tatsuya; Hoshina, Masayuki; Kudo, Tetsuhiro

    2017-04-01

    We investigate the optical manipulation of nanoparticles with the resonant nonlinear optical response. Efficient trapping of nanoparticles observed in experiments under the resonance condition is elucidated by considering optical nonlinearity. Also, we propose the flexible optical manipulations of nanoparticles that have gain by optical pumping. The pulling force and the rotational switching are demonstrated, where the stimulated emission from nanoparticles with inverted population is considered. These results show that utilizing nonlinear optical effect will greatly enhance the degrees of freedom to manipulate nanoparticles.

  14. Nanoparticle enhanced ionic liquid heat transfer fluids

    DOEpatents

    Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Gray, Joshua R.; Garcia-Diaz, Brenda L.

    2014-08-12

    A heat transfer fluid created from nanoparticles that are dispersed into an ionic liquid is provided. Small volumes of nanoparticles are created from e.g., metals or metal oxides and/or alloys of such materials are dispersed into ionic liquids to create a heat transfer fluid. The nanoparticles can be dispersed directly into the ionic liquid during nanoparticle formation or the nanoparticles can be formed and then, in a subsequent step, dispersed into the ionic liquid using e.g., agitation.

  15. Adhesion of oxide layer to metal-doped aluminum hydride surface: Density functional calculations

    NASA Astrophysics Data System (ADS)

    Takezawa, Tomoki; Itoi, Junichi; Kannan, Takashi

    2017-07-01

    The density functional theory (DFT) calculations were carried out to evaluate the adhesion energy of the oxide layer to the metal-doped surface of hydrogen storage material, aluminum hydride (alane, AlH3). The total energy calculations using slab model revealed that the surface doping of some metals to aluminum hydride weakens the adhesion strength of the oxide layer. The influence of titanium, iron, cobalt, and zirconium doping on adhesion strength were evaluated. Except for iron doping, the adhesion strength becomes weak by the doping.

  16. Ring-expansion reaction of oximes with aluminum reductants.

    PubMed

    Cho, Hidetsura; Iwama, Yusuke; Mitsuhashi, Nakako; Sugimoto, Kenji; Okano, Kentaro; Tokuyama, Hidetoshi

    2012-06-14

    The ring-expansion reactions of heterocyclic ketoximes and carbocyclic ketoximes with several reductants such as AlHCl2, AlH3 (alane), LiAlH4, LiAlH(OtBu)3, and (MeOCH2CH2O)2AlH2Na (Red-Al) were examined. Among reductants, AlHCl2 (LiAlH4:AlCl3 = 1:3) in cyclopentyl methyl ether (CPME) has been found to be a suitable reagent for the reaction, and the rearranged cyclic secondary amines were obtained in good to excellent yields.

  17. Al6H18: A baby crystal of γ-AlH3

    NASA Astrophysics Data System (ADS)

    Kiran, B.; Kandalam, Anil K.; Xu, Jing; Ding, Y. H.; Sierka, M.; Bowen, K. H.; Schnöckel, H.

    2012-10-01

    Using global-minima search methods based on the density functional theory calculations of (AlH3)n (n = 1-8) clusters, we show that the growth pattern of alanes for n ≥ 4 is dominated by structures containing hexa-coordinated Al atoms. This is in contrast to the earlier studies where either linear or ring structures of AlH3 were predicted to be the preferred structures in which the Al atoms can have a maximum of five-fold coordination. Our calculations also reveal that the Al6H18 cluster, with its hexa-coordination of the Al atoms, resembles the unit-cell of γ-AlH3, thus Al6H18 is designated as the "baby crystal." The fragmentation energies of the (AlH3)n (n = 2-8) along with the dimerization energies for even n clusters indicate an enhanced stability of the Al6H18 cluster. Both covalent (hybridization) and ionic (charge) contribution to the bonding are the driving factors in stabilizing the isomers containing hexa-coordinated Al atoms.

  18. Al6H18: a baby crystal of γ-AlH3.

    PubMed

    Kiran, B; Kandalam, Anil K; Xu, Jing; Ding, Y H; Sierka, M; Bowen, K H; Schnöckel, H

    2012-10-07

    Using global-minima search methods based on the density functional theory calculations of (AlH(3))(n) (n = 1-8) clusters, we show that the growth pattern of alanes for n ≥ 4 is dominated by structures containing hexa-coordinated Al atoms. This is in contrast to the earlier studies where either linear or ring structures of AlH(3) were predicted to be the preferred structures in which the Al atoms can have a maximum of five-fold coordination. Our calculations also reveal that the Al(6)H(18) cluster, with its hexa-coordination of the Al atoms, resembles the unit-cell of γ-AlH(3), thus Al(6)H(18) is designated as the "baby crystal." The fragmentation energies of the (AlH(3))(n) (n = 2-8) along with the dimerization energies for even n clusters indicate an enhanced stability of the Al(6)H(18) cluster. Both covalent (hybridization) and ionic (charge) contribution to the bonding are the driving factors in stabilizing the isomers containing hexa-coordinated Al atoms.

  19. Precise quantification of nanoparticle internalization.

    PubMed

    Gottstein, Claudia; Wu, Guohui; Wong, Benjamin J; Zasadzinski, Joseph Anthony

    2013-06-25

    Nanoparticles have opened new exciting avenues for both diagnostic and therapeutic applications in human disease, and targeted nanoparticles are increasingly used as specific drug delivery vehicles. The precise quantification of nanoparticle internalization is of importance to measure the impact of physical and chemical properties on the uptake of nanoparticles into target cells or into cells responsible for rapid clearance. Internalization of nanoparticles has been measured by various techniques, but comparability of data between different laboratories is impeded by lack of a generally accepted standardized assay. Furthermore, the distinction between associated and internalized particles has been a challenge for many years, although this distinction is critical for most research questions. Previously used methods to verify intracellular location are typically not quantitative and do not lend themselves to high-throughput analysis. Here, we developed a mathematical model which integrates the data from high-throughput flow cytometry measurements with data from quantitative confocal microscopy. The generic method described here will be a useful tool in biomedical nanotechnology studies. The method was then applied to measure the impact of surface coatings of vesosomes on their internalization by cells of the reticuloendothelial system (RES). RES cells are responsible for rapid clearance of nanoparticles, and the resulting fast blood clearance is one of the major challenges in biomedical applications of nanoparticles. Coating of vesosomes with long chain polyethylene glycol showed a trend for lower internalization by RES cells.

  20. Synthesis of noble metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Bahadory, Mozhgan

    Improved methods were developed for the synthesis of noble metal nanoparticles. Laboratory experiments were designed for introducing of nanotechnology into the undergraduate curriculum. An optimal set of conditions for the synthesis of clear yellow colloidal silver was investigated. Silver nanoparticles were obtained by borohydride reduction of silver nitrate, a method which produces particles with average size of 12+/-2 nm, determined by Transmission Electron Microscopy (TEM). The plasmon absorbance is at 397 nm and the peak width at half maximum (PWHM) is 70-75 nm. The relationship between aggregation and optical properties was determined along with a method to protect the particles using polyvinylpyrrolidone (PVP). A laboratory experiment was designed in which students synthesize yellow colloidal silver, estimate particle size using visible spectroscopy, and study aggregation effects. The synthesis of the less stable copper nanoparticles is more difficult because copper nanopaticles are easily oxidized. Four methods were used for the synthesis of copper nanoparticles, including chemical reduction with sodium borohydride, sodium borohydride with potassium iodide, isopropyl alcohol with cetyltrimethylammonium bormide (CTAB) and reducing sugars. The latter method was also the basis for an undergraduate laboratory experiment. For each reaction, the dependence of stability of the copper nanoparticles on reagent concentrations, additives, relative amounts of reactants, and temperature is explored. Atomic force microscopy (AFM), TEM and UV-Visible Spectroscopy were used to characterize the copper nanoparticles. A laboratory experiment to produce copper nanoparticles from household chemicals was developed.

  1. Magnetic nanoparticles for theragnostics

    PubMed Central

    Shubayev, Veronica I.; Pisanic, Thomas R.; Jin, Sungho

    2009-01-01

    Engineered magnetic nanoparticles (MNPs) represent a cutting-edge tool in medicine because they can be simultaneously functionalized and guided by a magnetic field. Use of MNPs has advanced magnetic resonance imaging (MRI), guided drug and gene delivery, magnetic hyperthermia cancer therapy, tissue engineering, cell tracking and bioseparation. Integrative therapeutic and diagnostic (i.e., theragnostic) applications have emerged with MNP use, such as MRI-guided cell replacement therapy or MRI-based imaging of cancer-specific gene delivery. However, mounting evidence suggests that certain properties of nanoparticles (e.g., enhanced reactive area, ability to cross cell and tissue barriers, resistance to biodegradation) amplify their cytotoxic potential relative to molecular or bulk counterparts. Oxidative stress, a 3-tier paradigm of nanotoxicity, manifests in activation of reactive oxygen species (ROS) (tier I), followed by a pro-inflammatory response (tier II) and DNA damage leading to cellular apoptosis and mutagenesis (tier III). In vivo administered MNPs are quickly challenged by macrophages of the reticuloendothelial system (RES), resulting in not only neutralization of potential MNP toxicity but also reduced circulation time necessary for MNP efficacy. We discuss the role of MNP size, composition and surface chemistry in their intracellular uptake, biodistribution, macrophage recognition and cytotoxicity, and review current studies on MNP toxicity, caveats of nanotoxicity assessments and engineering strategies to optimize MNPs for biomedical use. PMID:19389434

  2. Nanoparticle optical notch filters

    NASA Astrophysics Data System (ADS)

    Kasinadhuni, Pradeep Kumar

    Developing novel light blocking products involves the design of a nanoparticle optical notch filter, working on the principle of localized surface plasmon resonance (LSPR). These light blocking products can be used in many applications. One such application is to naturally reduce migraine headaches and light sensitivity. Melanopsin ganglion cells present in the retina of the human eye, connect to the suprachiasmatic nucleus (SCN-the body's clock) in the brain, where they participate in the entrainment of the circadian rhythms. As the Melanopsin ganglion cells are involved in triggering the migraine headaches in photophobic patients, it is necessary to block the part of visible spectrum that activates these cells. It is observed from the action potential spectrum of the ganglion cells that they absorb light ranging from 450-500nm (blue-green part) of the visible spectrum with a λmax (peak sensitivity) of around 480nm (blue line). Currently prescribed for migraine patients is the FL-41 coating, which blocks a broad range of wavelengths, including wavelengths associated with melanopsin absorption. The nanoparticle optical notch filter is designed to block light only at 480nm, hence offering an effective prescription for the treatment of migraine headaches.

  3. Taylor dispersion of nanoparticles

    NASA Astrophysics Data System (ADS)

    Balog, Sandor; Urban, Dominic A.; Milosevic, Ana M.; Crippa, Federica; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

    2017-08-01

    The ability to detect and accurately characterize particles is required by many fields of nanotechnology, including materials science, nanotoxicology, and nanomedicine. Among the most relevant physicochemical properties of nanoparticles, size and the related surface-to-volume ratio are fundamental ones. Taylor dispersion combines three independent phenomena to determine particle size: optical extinction, translational diffusion, and sheer-enhanced dispersion of nanoparticles subjected to a steady laminar flow. The interplay of these defines the apparent size. Considering that particles in fact are never truly uniform nor monodisperse, we rigorously address particle polydispersity and calculate the apparent particle size measured by Taylor dispersion analysis. We conducted case studies addressing aqueous suspensions of model particles and large-scale-produced "industrial" particles of both academic and commercial interest of various core materials and sizes, ranging from 15 to 100 nm. A comparison with particle sizes determined by transmission electron microscopy confirms that our approach is model-independent, non-parametric, and of general validity that provides an accurate account of size polydispersity—independently on the shape of the size distribution and without any assumption required a priori.

  4. Mesoporous metallic rhodium nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, Bo; Li, Cuiling; Dag, Ömer; Abe, Hideki; Takei, Toshiaki; Imai, Tsubasa; Hossain, Md. Shahriar A.; Islam, Md. Tofazzal; Wood, Kathleen; Henzie, Joel; Yamauchi, Yusuke

    2017-05-01

    Mesoporous noble metals are an emerging class of cutting-edge nanostructured catalysts due to their abundant exposed active sites and highly accessible surfaces. Although various noble metal (e.g. Pt, Pd and Au) structures have been synthesized by hard- and soft-templating methods, mesoporous rhodium (Rh) nanoparticles have never been generated via chemical reduction, in part due to the relatively high surface energy of rhodium (Rh) metal. Here we describe a simple, scalable route to generate mesoporous Rh by chemical reduction on polymeric micelle templates [poly(ethylene oxide)-b-poly(methyl methacrylate) (PEO-b-PMMA)]. The mesoporous Rh nanoparticles exhibited a ~2.6 times enhancement for the electrocatalytic oxidation of methanol compared to commercially available Rh catalyst. Surprisingly, the high surface area mesoporous structure of the Rh catalyst was thermally stable up to 400 °C. The combination of high surface area and thermal stability also enables superior catalytic activity for the remediation of nitric oxide (NO) in lean-burn exhaust containing high concentrations of O2.

  5. Nanoparticles and the Immune System

    PubMed Central

    Zolnik, Banu S.; González-Fernández, África; Sadrieh, Nakissa; Dobrovolskaia, Marina A.

    2010-01-01

    Today nanotechnology is finding growing applications in industry, biology, and medicine. The clear benefits of using nanosized products in various biological and medical applications are often challenged by concerns about the lack of adequate data regarding their toxicity. One area of interest involves the interactions between nanoparticles and the components of the immune system. Nanoparticles can be engineered to either avoid immune system recognition or specifically inhibit or enhance the immune responses. We review herein reported observations on nanoparticle-mediated immunostimulation and immunosuppression, focusing on possible theories regarding how manipulation of particle physicochemical properties can influence their interaction with immune cells to attain desirable immunomodulation and avoid undesirable immunotoxicity. PMID:20016026

  6. Inorganic Nanoparticles in Cancer Therapy

    PubMed Central

    Bhattacharyya, Sanjib; Kudgus, Rachel A.; Bhattacharya, Resham; Mukherjee, Priyabrata

    2011-01-01

    Nanotechnology is an evolving field with enormous potential for biomedical applications. The growing interest to use inorganic nanoparticles in medicine is due to the unique size and shape-dependent optoelectronic properties. Herein, we will focus on gold, silver and platinum nanoparticles, discussing recent developments for therapeutic applications with regard to cancer in terms of nanoparticles being used as a delivery vehicle as well as therapeutic agents. We will also discuss some of the key challenges to be addressed in future studies. PMID:21104301

  7. Method of synthesizing tungsten nanoparticles

    SciTech Connect

    Thoma, Steven G; Anderson, Travis M

    2013-02-12

    A method to synthesize tungsten nanoparticles has been developed that enables synthesis of nanometer-scale, monodisperse particles that can be stabilized only by tetrahydrofuran. The method can be used at room temperature, is scalable, and the product concentrated by standard means. Since no additives or stabilizing surfactants are required, this method is particularly well suited for producing tungsten nanoparticles for dispersion in polymers. If complete dispersion is achieved due to the size of the nanoparticles, then the optical properties of the polymer can be largely maintained.

  8. [Toxicity of nanoparticles on reproduction].

    PubMed

    Greco, F; Courbière, B; Rose, J; Orsière, T; Sari-Minodier, I; Bottero, J-Y; Auffan, M; Perrin, J

    2015-01-01

    Nanoparticles (NPs) are sized between 1 and 100nm. Their size allows new nanoscale properties of particular interest for industrial and scientific purpose. Over the past twenty years, nanotechnology conquered many areas of use (electronic, cosmetic, textile…). While, human is exposed to an increasing number of nanoparticles sources, health impacts and, particularly on reproductive function, remains poorly evaluated. Indeed, traceability of nanoparticles use is lacking and nanotoxicology follows different rules than classical toxicology. This review focuses on the impact of NPs on health and particularly on fertility and addresses potential risks of chronic exposure to NPs on human fertility. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  9. Dialysis nanoprecipitation of polystyrene nanoparticles.

    PubMed

    Zhang, Chuan; Chung, Jae Woo; Priestley, Rodney D

    2012-10-26

    Using a facile dialysis nanoprecipitation method, nanoparticles of several hundred nanometers have been successfully generated from a "traditional," non-biodegradable polymer, that is, polystyrene. The effect of initial polymer concentration inside the dialysis membrane, as well as the polymer/solvent system and the ionic strength (electrolyte concentration) of the dialysis solution, on nanoparticle size is examined. A nucleation-aggregation mechanism has been provided to explain the observed trends. Furthermore, we determine the zeta potential as a function of ionic strength for the generated nanoparticles and show that anionic charging may be present in the system. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Ionizing radiation increases systemic nanoparticle tumor accumulation

    PubMed Central

    Giustini, A.J.; Petryk, A.A.; Hoopes, P.J.

    2012-01-01

    Nanoparticle-based therapies are currently being explored for both the imaging and treatment of primary and metastatic cancers. Effective nanoparticle cancer therapy requires significant accumulations of nanoparticles within the tumor environment. Various techniques have been used to improve tumor nanoparticle uptake and biodistribution. Most notable of these techniques are the use of tumor-specific-peptide-conjugated nanoparticles and chemical modification of the nanoparticles with immune-evading polymers. Another strategy for improving the tumor uptake of the nanoparticles is modification of the tumor microenvironment with a goal of enhancing the enhanced permeability and retention effect inherent to solid tumors. We demonstrate a two-fold increase in the tumor accumulation of systemically delivered iron oxide nanoparticles following a single, 15 Gy radiation dose in a syngeneic mouse breast tumor model. This increase in nanoparticle tumor accumulation correlates with a radiation-induced decrease in tumor interstitial pressure and a subsequent increase in vascular permeability. PMID:22633900

  11. Effect of Nanoparticle Surface on the HPLC Elution Profile of Liposomal Nanoparticles.

    PubMed

    Itoh, Naoki; Yamamoto, Eiichi; Santa, Tomofumi; Funatsu, Takashi; Kato, Masaru

    2016-06-01

    Nanoparticles have been used in diverse areas, and even broader applications are expected in the future. Since surface modification can influence the configuration and toxicity of nanoparticles, a rapid screening method is important to ensure nanoparticle quality. We examined the effect of the nanoparticle surface morphology on the HPLC elution profile using two types of 100-nm liposomal nanoparticles (AmBisome(Ⓡ) and DOXIL(Ⓡ)). These 100-nm-sized nanoparticles eluted before the holdup time (about 4 min), even when a column packed with particles with a relatively large pore size (30 nm) was used. The elution time of the nanoparticles increased with pegylation of the nanoparticles and protein adsorption to the nanoparticles; however, the nanoparticles still eluted before the holdup time. The results of this study indicate that HPLC is a suitable tool for rapid evaluation of the surface of liposomal nanoparticles.

  12. Cellular Binding of Anionic Nanoparticles is Inhibited by Serum Proteins Independent of Nanoparticle Composition.

    PubMed

    Fleischer, Candace C; Kumar, Umesh; Payne, Christine K

    2013-09-01

    Nanoparticles used in biological applications encounter a complex mixture of extracellular proteins. Adsorption of these proteins on the nanoparticle surface results in the formation of a "protein corona," which can dominate the interaction of the nanoparticle with the cellular environment. The goal of this research was to determine how nanoparticle composition and surface modification affect the cellular binding of protein-nanoparticle complexes. We examined the cellular binding of a collection of commonly used anionic nanoparticles: quantum dots, colloidal gold nanoparticles, and low-density lipoprotein particles, in the presence and absence of extracellular proteins. These experiments have the advantage of comparing different nanoparticles under identical conditions. Using a combination of fluorescence and dark field microscopy, flow cytometry, and spectroscopy, we find that cellular binding of these anionic nanoparticles is inhibited by serum proteins independent of nanoparticle composition or surface modification. We expect these results will aid in the design of nanoparticles for in vivo applications.

  13. Nanoparticle delivery in infant lungs

    PubMed Central

    Semmler-Behnke, Manuela; Kreyling, Wolfgang G.; Schulz, Holger; Takenaka, Shinji; Butler, James P.; Henry, Frank S.; Tsuda, Akira

    2012-01-01

    The lung surface is an ideal pathway to the bloodstream for nanoparticle-based drug delivery. Thus far, research has focused on the lungs of adults, and little is known about nanoparticle behavior in the immature lungs of infants. Here, using nonlinear dynamical systems analysis and in vivo experimentation in developing animals, we show that nanoparticle deposition in postnatally developing lungs peaks at the end of bulk alveolation. This finding suggests a unique paradigm, consistent with the emerging theory that as alveoli form through secondary septation, alveolar flow becomes chaotic and chaotic mixing kicks in, significantly enhancing particle deposition. This finding has significant implications for the application of nanoparticle-based inhalation therapeutics in young children with immature lungs from birth to ˜2 y of age. PMID:22411799

  14. Missing Fe: hydrogenated iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Bilalbegović, G.; Maksimović, A.; Mohaček-Grošev, V.

    2017-03-01

    Although it was found that the FeH lines exist in the spectra of some stars, none of the spectral features in the interstellar medium (ISM) have been assigned to this molecule. We suggest that iron atoms interact with hydrogen and produce Fe-H nanoparticles which sometimes contain many H atoms. We calculate infrared spectra of hydrogenated iron nanoparticles using density functional theory methods and find broad, overlapping bands. Desorption of H2 could induce spinning of these small Fe-H dust grains. Some of hydrogenated iron nanoparticles possess magnetic and electric moments and should interact with electromagnetic fields in the ISM. FenHm nanoparticles could contribute to the polarization of the ISM and the anomalous microwave emission. We discuss the conditions required to form FeH and FenHm in the ISM.

  15. Nanoparticle Solutions for Printed Electronics

    DTIC Science & Technology

    2013-09-19

    titania , silica) were investigated in the production of complementary inks for complex devices. These were either obtained commercially in... titania nanoparticles, with the electrolyte or semiconducting polymer between. Unlike conventional photochemical cells, the cell under development does

  16. Imaging techniques: Nanoparticle atoms pinpointed

    NASA Astrophysics Data System (ADS)

    Farle, Michael

    2017-02-01

    The locations of atoms in a metallic alloy nanoparticle have been determined using a combination of electron microscopy and image simulation, revealing links between the particle's structure and magnetic properties. See Letter p.75

  17. Lipid nanoparticle interactions and assemblies

    NASA Astrophysics Data System (ADS)

    Preiss, Matthew Ryan

    Novel liposome-nanoparticle assemblies (LNAs) provide a biologically inspired route for designing multifunctional bionanotheranostics. LNAs combine the benefits of lipids and liposomes to encapsulate, transport, and protect hydrophilic and hydrophobic therapeutics with functional nanoparticles. Functional nanoparticles endow LNAs with additional capabilities, including the ability to target diseases, triggered drug release, controlled therapeutic output, and diagnostic capabilities to produce a drug delivery system that can effectively and efficiently deliver therapeutics while reducing side effects. Not only could LNAs make existing drugs better, they could also provide an avenue to allow once promising non-approved drugs (rejected due to harmful side effects, inadequate pharmacokinetics, and poor efficacy) to be safely used through targeted and controlled delivery directly to the diseased site. LNAs have the potential to be stimuli responsive, delivering drugs on command by external (ultrasound, RF heating, etc.) or internal (pH, blood sugar, heart rate, etc.) stimuli. Individually, lipids and nanoparticles have been clinically approved for therapy, such as Doxil (a liposomal doxorubicin for cancer treatment), and diagnosis, such as Feridex (an iron oxide nanoparticle an MRI contrast enhancement agent for liver tumors). In order to engineer these multifunctional LNAs for theranostic applications, the interactions between nanoparticles and lipids must be better understood. This research sought to explore the formation, design, structures, characteristics, and functions of LNAs. To achieve this goal, different types of LNAs were formed, specifically magnetoliposomes, bilayer decorated LNAs (DLNAs), and lipid-coated magnetic nanoparticles (LMNPs). A fluorescent probe was embedded in the lipid bilayer of magnetoliposomes allowing the local temperature and membrane fluidity to be observed. When subjected to an electromagnetic field that heated the encapsulated iron

  18. Electrical sintering of nanoparticle structures.

    PubMed

    Allen, Mark L; Aronniemi, Mikko; Mattila, Tomi; Alastalo, Ari; Ojanperä, Kimmo; Suhonen, Mika; Seppä, Heikki

    2008-04-30

    A method for sintering nanoparticles by applying voltage is presented. This electrical sintering method is demonstrated using silver nanoparticle structures ink-jet-printed onto temperature-sensitive photopaper. The conductivity of the printed nanoparticle layer increases by more than five orders of magnitude during the sintering process, with the final conductivity reaching 3.7 × 10(7) S m(-1) at best. Due to a strong positive feedback induced by the voltage boundary condition, the process is very rapid-the major transition occurs within 2 µs. The best obtained conductivity is two orders of magnitude better than for the equivalent structures oven-sintered at the maximum tolerable temperature of the substrate. Additional key advantages of the method include the feasibility for patterning, systematic control of the final conductivity and in situ process monitoring. The method offers a generic tool for electrical functionalization of nanoparticle structures.

  19. Multiscaffold DNA Origami Nanoparticle Waveguides

    PubMed Central

    2013-01-01

    DNA origami templated self-assembly has shown its potential in creating rationally designed nanophotonic devices in a parallel and repeatable manner. In this investigation, we employ a multiscaffold DNA origami approach to fabricate linear waveguides of 10 nm diameter gold nanoparticles. This approach provides independent control over nanoparticle separation and spatial arrangement. The waveguides were characterized using atomic force microscopy and far-field polarization spectroscopy. This work provides a path toward large-scale plasmonic circuitry. PMID:23841957

  20. Method for producing metallic nanoparticles

    DOEpatents

    Phillips, Jonathan; Perry, William L.; Kroenke, William J.

    2004-02-10

    Method for producing metallic nanoparticles. The method includes generating an aerosol of solid metallic microparticles, generating non-oxidizing plasma with a plasma hot zone at a temperature sufficiently high to vaporize the microparticles into metal vapor, and directing the aerosol into the hot zone of the plasma. The microparticles vaporize in the hot zone to metal vapor. The metal vapor is directed away from the hot zone and to the plasma afterglow where it cools and condenses to form solid metallic nanoparticles.

  1. Diamond Synthesis Employing Nanoparticle Seeds

    NASA Technical Reports Server (NTRS)

    Uppireddi, Kishore (Inventor); Morell, Gerardo (Inventor); Weiner, Brad R. (Inventor)

    2014-01-01

    Iron nanoparticles were employed to induce the synthesis of diamond on molybdenum, silicon, and quartz substrates. Diamond films were grown using conventional conditions for diamond synthesis by hot filament chemical vapor deposition, except that dispersed iron oxide nanoparticles replaced the seeding. This approach to diamond induction can be combined with dip pen nanolithography for the selective deposition of diamond and diamond patterning while avoiding surface damage associated to diamond-seeding methods.

  2. Modern Nanoparticle Research in Russia

    NASA Astrophysics Data System (ADS)

    Andrievski, R. A.

    2003-12-01

    Nanoparticle and nanomaterial research has become one of the most active frontier areas. In Russia and countries of the former Soviet Union work devoted to the thorough study of ultrafine media (low-dimensional subjects) started early. In the present paper a short historical review is given and the problems of nanoparticle research in Russia and some related fields (such as nanomaterials, nanochemistry, and nanophysics) are discussed.

  3. Modeling biological activities of nanoparticles.

    PubMed

    Epa, V Chandana; Burden, Frank R; Tassa, Carlos; Weissleder, Ralph; Shaw, Stanley; Winkler, David A

    2012-11-14

    Products are increasingly incorporating nanomaterials, but we have a poor understanding of their adverse effects. To assess risk, regulatory authorities need more experimental testing of nanoparticles. Computational models play a complementary role in allowing rapid prediction of potential toxicities of new and modified nanomaterials. We generated quantitative, predictive models of cellular uptake and apoptosis induced by nanoparticles for several cell types. We illustrate the potential of computational methods to make a contribution to nanosafety.

  4. Functionalized magnetic nanoparticle analyte sensor

    DOEpatents

    Yantasee, Wassana; Warner, Maryin G; Warner, Cynthia L; Addleman, Raymond S; Fryxell, Glen E; Timchalk, Charles; Toloczko, Mychailo B

    2014-03-25

    A method and system for simply and efficiently determining quantities of a preselected material in a particular solution by the placement of at least one superparamagnetic nanoparticle having a specified functionalized organic material connected thereto into a particular sample solution, wherein preselected analytes attach to the functionalized organic groups, these superparamagnetic nanoparticles are then collected at a collection site and analyzed for the presence of a particular analyte.

  5. Nanoparticles Containing Insoluble Drug for Cancer Therapy

    PubMed Central

    Guo, Shutao; Huang, Leaf

    2014-01-01

    Nanoparticle drug formulations have been extensively researched and developed in the field of drug delivery as a means to efficiently deliver insoluble drugs to tumor cells. By mechanisms of the enhanced permeability and retention effect, nanoparticle drug formulations are capable of greatly enhancing the safety, pharmacokinetic profiles and bioavailability of the administered treatment. Here, the progress of various nanoparticle formulations in both research and clinical applications is detailed with a focus on the development of drug/gene delivery systems. Specifically, the unique advantages and disadvanges of polymeric nanoparticles, liposomes, solid lipid nanoparticles, nanocrystals and lipid-coated nanoparticles for targeted drug delivery will be investigated in detail. PMID:24113214

  6. Nanoparticle fluorescence based technology for biological applications.

    PubMed

    Chen, Wei

    2008-03-01

    Fluorescence is widely used in biological detection and imaging. The emerging luminescent nanoparticles or quantum dots provide a new type of biological agents that can improve these applications. The advantages of luminescent nanoparticles for biological applications include their high quantum yield, color availability, good photo-stability, large surface-to-volume ratio, surface functionality, and small size. In this review article, we first introduce quantum size confinement, photoluminescence and upconversion luminescence of nanoparticles, then describe the preparation and conjugation of water soluble nanoparticles and introduce the applications of luminescence nanoparticles for in vitro and in vivo imaging, fluorescence resonance energy based detection, and the applications of luminescence nanoparticles for photodynamic activation.

  7. Non-Engineered Nanoparticles of C60

    PubMed Central

    Deguchi, Shigeru; Mukai, Sada-atsu; Sakaguchi, Hide; Nonomura, Yoshimune

    2013-01-01

    We discovered that rubbing bulk solids of C60 between fingertips generates nanoparticles including the ones smaller than 20 nm. Considering the difficulties usually associated with nanoparticle production by pulverisation, formation of nanoparticles by such a mundane method is unprecedented and noteworthy. We also found that nanoparticles of C60 could be generated from bulk solids incidentally without deliberate engineering of any sort. Our findings imply that there exist highly unusual human exposure routes to nanoparticles of C60, and elucidating formation mechanisms of nanoparticles is crucial in assessing their environmental impacts. PMID:23807024

  8. Biosensors Incorporating Bimetallic Nanoparticles.

    PubMed

    Rick, John; Tsai, Meng-Che; Hwang, Bing Joe

    2015-12-31

    This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today's society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given.

  9. Metal nanoparticles for biodetection

    NASA Astrophysics Data System (ADS)

    Oldenburg, Steven; Mock, Jack; Glass, James R.; Asenjo, Ana B.; Genick, Christine C.; Smith, David R.; Schultz, David A.; Schultz, Sheldon

    2002-10-01

    The large scattering cross section of plasmon resonant gold and silver nanoparticles functionalized with the appropriate ligand allows for sensitive and specific detection of nucleic acids and proteins. By varying the size, shape, and material morphology populations with a specific peak plasmon resonance can be prepared. By varying the order and length of plasmon resonant bar segment in a composite nanowire one can obtain a large number of particle populations. Distinct populations can be used for labels for multiplexing or as a platform for biological assays. An larger number of color populations can be obtained with composite nanowires that are fabricated with various lengths of silver, gold, or nickel segments. The order and length of the different plasmon resonance rod segments can be used to uniquely identify a rod population allowing for a large degree of multiplexing within a single sample.

  10. Enriching Nanoparticles via Acoustofluidics.

    PubMed

    Mao, Zhangming; Li, Peng; Wu, Mengxi; Bachman, Hunter; Mesyngier, Nicolas; Guo, Xiasheng; Liu, Sheng; Costanzo, Francesco; Huang, Tony Jun

    2017-01-24

    Focusing and enriching submicrometer and nanometer scale objects is of great importance for many applications in biology, chemistry, engineering, and medicine. Here, we present an acoustofluidic chip that can generate single vortex acoustic streaming inside a glass capillary through using low-power acoustic waves (only 5 V is required). The single vortex acoustic streaming that is generated, in conjunction with the acoustic radiation force, is able to enrich submicrometer- and nanometer-sized particles in a small volume. Numerical simulations were used to elucidate the mechanism of the single vortex formation and were verified experimentally, demonstrating the focusing of silica and polystyrene particles ranging in diameter from 80 to 500 nm. Moreover, the acoustofluidic chip was used to conduct an immunoassay in which nanoparticles that captured fluorescently labeled biomarkers were concentrated to enhance the emitted signal. With its advantages in simplicity, functionality, and power consumption, the acoustofluidic chip we present here is promising for many point-of-care applications.

  11. Biosensors Incorporating Bimetallic Nanoparticles

    PubMed Central

    Rick, John; Tsai, Meng-Che; Hwang, Bing Joe

    2015-01-01

    This article presents a review of electrochemical bio-sensing for target analytes based on the use of electrocatalytic bimetallic nanoparticles (NPs), which can improve both the sensitivity and selectivity of biosensors. The review moves quickly from an introduction to the field of bio-sensing, to the importance of biosensors in today’s society, the nature of the electrochemical methods employed and the attendant problems encountered. The role of electrocatalysts is introduced with reference to the three generations of biosensors. The contributions made by previous workers using bimetallic constructs, grouped by target analyte, are then examined in detail; following which, the synthesis and characterization of the catalytic particles is examined prior to a summary of the current state of endeavor. Finally, some perspectives for the future of bimetallic NPs in biosensors are given. PMID:28344262

  12. Polyelemental nanoparticle libraries

    NASA Astrophysics Data System (ADS)

    Chen, Peng-Cheng; Liu, Xiaolong; Hedrick, James L.; Xie, Zhuang; Wang, Shunzhi; Lin, Qing-Yuan; Hersam, Mark C.; Dravid, Vinayak P.; Mirkin, Chad A.

    2016-06-01

    Multimetallic nanoparticles are useful in many fields, yet there are no effective strategies for synthesizing libraries of such structures, in which architectures can be explored in a systematic and site-specific manner. The absence of these capabilities precludes the possibility of comprehensively exploring such systems. We present systematic studies of individual polyelemental particle systems, in which composition and size can be independently controlled and structure formation (alloy versus phase-separated state) can be understood. We made libraries consisting of every combination of five metallic elements (Au, Ag, Co, Cu, and Ni) through polymer nanoreactor-mediated synthesis. Important insight into the factors that lead to alloy formation and phase segregation at the nanoscale were obtained, and routes to libraries of nanostructures that cannot be made by conventional methods were developed.

  13. Nanoparticles and Neurotoxicity

    PubMed Central

    Win-Shwe, Tin-Tin; Fujimaki, Hidekazu

    2011-01-01

    Humans are exposed to nanoparticles (NPs; diameter < 100 nm) from ambient air and certain workplaces. There are two main types of NPs; combustion-derived NPs (e.g., particulate matters, diesel exhaust particles, welding fumes) and manufactured or engineered NPs (e.g., titanium dioxide, carbon black, carbon nanotubes, silver, zinc oxide, copper oxide). Recently, there have been increasing reports indicating that inhaled NPs can reach the brain and may be associated with neurodegeneration. It is necessary to evaluate the potential toxic effects of NPs on brain because most of the neurobehavioral disorders may be of environmental origin. This review highlights studies on both combustion-derived NP- and manufactured or engineered NP-induced neuroinflammation, oxidative stress, and gene expression, as well as the possible mechanism of these effects in animal models and in humans. PMID:22016657

  14. Exposure to Nanoparticles and Hormesis

    PubMed Central

    Iavicoli, Ivo; Calabrese, Edward J.; Nascarella, Marc A.

    2010-01-01

    Nanoparticles are particles with lengths that range from 1 to 100 nm. They are increasingly being manufactured and used for commercial purpose because of their novel and unique physicochemical properties. Although nanotechnology-based products are generally thought to be at a pre-competitive stage, an increasing number of products and materials are becoming commercially available. Human exposure to nanoparticles is therefore inevitable as they become more widely used and, as a result, nanotoxicology research is now gaining attention. However, there are many uncertainties as to whether the unique properties of nanoparticles also pose occupational health risks. These uncertainties arise because of gaps in knowledge about the factors that are essential for predicting health risks such as routes of exposure, distribution, accumulation, excretion and dose-response relationship of the nanoparticles. In particular, uncertainty remains with regard to the nature of the dose-response curve at low level exposures below the toxic threshold. In fact, in the literature, some studies that investigated the biological effects of nanoparticles, observed a hormetic dose-response. However, currently available data regarding this topic are extremely limited and fragmentary. It therefore seems clear that future studies need to focus on this issue by studying the potential adverse health effects caused by low-level exposures to nanoparticles. PMID:21191487

  15. Magentite nanoparticle for arsenic remotion.

    NASA Astrophysics Data System (ADS)

    Viltres, H.; Odio, O. F.; Borja, R.; Aguilera, Y.; Reguera, E.

    2017-01-01

    Inorganic As (V) and As (III) species are commonly found in groundwater in many countries around the world. It is known that arsenic is highly toxic and carcinogenic, at present exist reports of diverse countries with arsenic concentrations in drinking water higher than those proposed by the World Health Organization (10 μg/L). It has been reported that adsorption strategies using magnetic nanoparticles as magnetite (<20 nm) proved to be very efficient for the removal of arsenic in drinking water. Magnetic nanoparticles (magnetite) were prepared using a co-precipitation method with FeCl3 and FeCl2 as metal source and NaOH aqueous solution as precipitating agent. Magnetite nanoparticles synthesized were put in contact with As2O3 and As2O5 solutions at room temperature to pH 4 and 7. The nanoparticles were characterized by FT-IR, DRX, UV-vis, and XRF. The results showed that synthesized magnetite had an average diameter of 11 nm and a narrow size distribution. The presence of arsenic on magnetite nanoparticles surface was confirmed, which is more remarkable when As (V) is employed. Besides, it is possible to observe that no significant changes in the band gap values after adsorption of arsenic in the nanoparticles.

  16. Biomedical applications of gold nanoparticles.

    PubMed

    Cabuzu, Daniela; Cirja, Andreea; Puiu, Rebecca; Grumezescu, Alexandru Mihai

    2015-01-01

    Gold nanoparticles may be used in different domains, one of most important being the biomedical field. They have suitable properties for controlled drug delivery, cancer treatment, biomedical imaging, diagnosis and many others, due to their excellent compatibility with the human organism, low toxicity and tunable stability, small dimensions, and possibility to interact with a variety of substances. They also have optical properties, being able to absorb infrared light. Moreover, due to their large surface and the ability of being coated with a variety of therapeutic agents, gold nanoparticles have been showed a great potential to be used as drug delivery systems. Gold nanoparticles are intensively studied in biomedicine, and recent studies revealed the fact that they can cross the blood-brain barrier, may interact with the DNA and produce genotoxic effects. Because of their ability of producing heat, they can target and kill the tumors, being used very often in photodynamic therapy. Gold nanoparticles can be synthesized in many ways, but the most common are the biological and chemical methods, however the chemical method offers the advantage of better controlling the size and shape of the nanoparticles. In this review, we present the principal applications of gold nanoparticles in the biomedical field, like cancer treatment, amyloid-like fibrillogenesis inhibitors, transplacental treatment, the development of specific scaffolds and drug delivery systems.

  17. Hydrogen Adsorption in Carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Cabrera, A. L.; Rojas, S.; Dias-Droguett, D. E.; Bhuyan, H.; Aomoa, N.; Kakati, M.

    2013-03-01

    We have studied hydrogen adsorption in carbon nanoparticles using a quartz crystal microbalance. The carbon nanoparticles were synthesized from a thermal plasma jet at different pressure (15 - 263 torr) of the reactants and different current (50 - 250 A) to generate the plasma. The as-prepared carbon nanoparticles were directly deposited on top of the gold electrode of a quartz crystal and we monitored in-situ the changes in resonance frequency while the chamber was pressurized at different hydrogen pressures. These changes enabled determination of absorbed hydrogen mass in order to get H/C mass ratio curves as a function of H2 pressure. Adsorption curves obtained in some carbon nanoparticles indicated the formation of hydrogen monolayer inside the pores of the carbon nanoparticles. Using the value of the jump due to the formation of a H2\\ monolayer, a surface area was estimated between 40-60 m2/g for hydrogen adsorption. In other carbon samples, hydrogen uptake curves indicated that H2 was filling the sample's pores when pore volume was large. These observations will be discussed in detail for several carbon nanoparticles samples. Funds provided by VRI Puente 9/2012 and 10/2012

  18. Magnetic Nanoparticles for Biomedical Applications

    NASA Astrophysics Data System (ADS)

    Jing, Ying

    Nanotechnology is revolutionizing human's life. Synthesis and application of magnetic nanoparticles is a fast burgeoning field which has potential to bring significant advance in many fields, for example diagnosis and treatment in biomedical area. Novel nanoparticles to function efficiently and intelligently are in desire to improve the current technology. We used a magnetron-sputtering-based nanocluster deposition technique to synthesize magnetic nanoparticles in gas phase, and specifically engineered nanoparticles for different applications. Alternating magnetic field heating is emerging as a technique to assist cancer treatment or drug delivery. We proposed high-magnetic-moment Fe3Si particles with relatively large magnetic anisotropy energy should in principle provide superior performance. Such nanoparticles were experimentally synthesized and characterized. Their promising magnetic properties can contribute to heating performance under suitable alternating magnetic field conditions. When thermal energy is used for medical treatment, it is ideal to work in a designed temperature range. Biocompatible and "smart" magnetic nanoparticles with temperature self-regulation were designed from both materials science and biomedicine aspects. We chose Fe-Si material system to demonstrate the concept. Temperature dependent physical property was adjusted by tuning of exchange coupling between Fe atoms through incorporation of various amount of Si. The magnetic moment can still be kept in a promising range. The two elements are both biocompatible, which is favored by in-vivo medical applications. A combination of "smart" magnetic particles and thermo-sensitive polymer were demonstrated to potentially function as a platform for drug delivery. Highly sensitive diagnosis for point-of-care is in desire nowadays. We developed composition- and phase-controlled Fe-Co nanoparticles for bio-molecule detection. It has been demonstrated that Fe70Co30 nanoparticles and giant

  19. Development of polymeric–cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery

    PubMed Central

    Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

    2015-01-01

    We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid–polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA. PMID:26648722

  20. Development of polymeric-cationic peptide composite nanoparticles, a nanoparticle-in-nanoparticle system for controlled gene delivery.

    PubMed

    Jain, Arvind K; Massey, Ashley; Yusuf, Helmy; McDonald, Denise M; McCarthy, Helen O; Kett, Vicky L

    2015-01-01

    We report the formulation of novel composite nanoparticles that combine the high transfection efficiency of cationic peptide-DNA nanoparticles with the biocompatibility and prolonged delivery of polylactic acid-polyethylene glycol (PLA-PEG). The cationic cell-penetrating peptide RALA was used to condense DNA into nanoparticles that were encapsulated within a range of PLA-PEG copolymers. The composite nanoparticles produced exhibited excellent physicochemical properties including size <200 nm and encapsulation efficiency >80%. Images of the composite nanoparticles obtained with a new transmission electron microscopy staining method revealed the peptide-DNA nanoparticles within the PLA-PEG matrix. Varying the copolymers modulated the DNA release rate >6 weeks in vitro. The best formulation was selected and was able to transfect cells while maintaining viability. The effect of transferrin-appended composite nanoparticles was also studied. Thus, we have demonstrated the manufacture of composite nanoparticles for the controlled delivery of DNA.

  1. Creation of "bonding structures" on nanoparticles

    NASA Astrophysics Data System (ADS)

    Zheng, Wan

    Nanoparticles can be used as a new type of fundamental building blocks to construct macroscopic materials, and hierarchically organized nanoparticles often show enhanced properties originated from the collective interactions among these individual nanoscale building blocks. Taking one step further, colloidal molecules with well-defined architectures made by directed assembly of nanoparticles could serve as the basic structural units of more complex functional materials. This is highly desirable but challenging due to the lack of "bonding structures" on nanoparticles. In this thesis, we aim to create "bonding structures" on nanoparticles by modifying them with heterogeneously functionalized polymers bearing "click" moieties. We hypothesize that by controlling the location of "click" recognition pairs on nanoparticles, well-defined polymer linkers, nanoparticle geometry and reaction stoichiometry, the "directionality", "bonding length", and "valency" characteristics of real chemical bonds could be introduced on as-synthesized nanoparticles, which will help organize nanoparticles into colloidal molecules via highly specific and efficient "click" reactions. Using gold nanoparticles as models, we show here that well-defined, heterogeneously functionalized polymer chains bearing "click" recognition pairs can be prepared, and subsequently used to modify gold nanoparticles at controlled locations. Our future work is to study the broad utility of this strategy on creating "bonding structures" on nanoparticles to transform them into "artificial atoms", as well as the system design to assemble these nanoparticles into well-defined colloidal molecules.

  2. Ultrasound mediated nanoparticle drug delivery

    NASA Astrophysics Data System (ADS)

    Mullin, Lee B.

    Ultrasound is not only a powerful diagnostic tool, but also a promising therapeutic technology that can be used to improve localized drug delivery. Microbubble contrast agents are micron sized encapsulated gas filled bubbles that are administered intravenously. Originally developed to enhance ultrasound images, microbubbles are highly echogenic due to the gas core that provides a detectable impedance difference from the surrounding medium. The core also allows for controlled response of the microbubbles to ultrasound pulses. Microbubbles can be pushed using acoustic radiation force and ruptured using high pressures. Destruction of microbubbles can increase permeability at the cellular and vascular level, which can be advantageous for drug delivery. Advances in drug delivery methods have been seen with the introduction of nanoparticles, nanometer sized objects often carrying a drug payload. In chemotherapy, nanoparticles can deliver drugs to tumors while limiting systemic exposure due to abnormalities in tumor vasculature such large gaps between endothelial cells that allow nanoparticles to enter into the interstitial space; this is referred to as the enhanced permeability and retention (EPR) effect. However, this effect may be overestimated in many tumors. Additionally, only a small percentage of the injected dose accumulates in the tumor, which most the nanoparticles accumulating in the liver and spleen. It is hypothesized that combining the acoustic activity of an ultrasound contrast agent with the high payload and extravasation ability of a nanoparticle, localized delivery to the tumor with reduced systemic toxicity can be achieved. This method can be accomplished by either loading nanoparticles onto the shell of the microbubble or through a coadministration method of both nanoparticles and microbubbles. The work presented in this dissertation utilizes novel and commercial nanoparticle formulations, combined with microbubbles and a variety of ultrasound systems

  3. Interaction of nanoparticles with proteins: relation to bio-reactivity of the nanoparticle.

    PubMed

    Saptarshi, Shruti R; Duschl, Albert; Lopata, Andreas L

    2013-07-19

    Interaction of nanoparticles with proteins is the basis of nanoparticle bio-reactivity. This interaction gives rise to the formation of a dynamic nanoparticle-protein corona. The protein corona may influence cellular uptake, inflammation, accumulation, degradation and clearance of the nanoparticles. Furthermore, the nanoparticle surface can induce conformational changes in adsorbed protein molecules which may affect the overall bio-reactivity of the nanoparticle. In depth understanding of such interactions can be directed towards generating bio-compatible nanomaterials with controlled surface characteristics in a biological environment. The main aim of this review is to summarise current knowledge on factors that influence nanoparticle-protein interactions and their implications on cellular uptake.

  4. Synthesis and Characterization of Environmentally Benign Nanoparticles

    EPA Science Inventory

    There has been a growing interest in replacing current non-biodegradable and toxic nanosystems with environmentally benign biopolymer based ones to minimize post-utilization hazards due to uncontrolled accumulation of nanoparticles in the environment. Lignin based nanoparticles (...

  5. Synthesis and Characterization of Environmentally Benign Nanoparticles

    EPA Science Inventory

    There has been a growing interest in replacing current non-biodegradable and toxic nanosystems with environmentally benign biopolymer based ones to minimize post-utilization hazards due to uncontrolled accumulation of nanoparticles in the environment. Lignin based nanoparticles (...

  6. Thermal resistance between amorphous silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Meng, Fanhe; Elsahati, Muftah; Liu, Jin; Richards, Robert F.

    2017-05-01

    Nanoparticle-based materials have been used as thermal insulation in a variety of macroscale and microscale applications. In this work, we investigate the heat transfer between nanoparticles using non-equilibrium molecular dynamics simulations. We calculate the total thermal resistance and thermal boundary resistance between adjacent amorphous silica nanoparticles. Numerical results are compared to interparticle resistances determined from experimental measurements of heat transfer across packed silica nanoparticle beds. The thermal resistance between nanoparticles is shown to increase rapidly as the particle contact radius decreases. More significantly, the interparticle resistance depends strongly on the forces between particles, in particular, the presence or absence of chemical bonds between nanoparticles. In addition, the effect of interfacial force strength on thermal resistance increases as the nanoparticle diameter decreases. The simulations results are shown to be in good agreement with experimental results for 20 nm silica nanoparticles.

  7. Ferritin protein encapsulated photoluminescent rare earth nanoparticle

    NASA Astrophysics Data System (ADS)

    Harada, T.; Yoshimura, H.

    2013-07-01

    Rare earth (yttrium (Y), europium (Eu), and terbium (Tb)) nanoparticles and Eu and Tb doped Y nanoparticles are synthesized in an apoferritin cavity. They exhibit a narrow size distribution and a high stability in an aqueous solution at pH 8.5. Eu and Eu doped Y (Y:Eu) nanoparticles exhibit red photoluminescence (emission peaks: 590 and 614 nm), while Tb and Tb doped Y (Y:Tb) nanoparticles exhibit green photoluminescence (emission peaks: 488, 544, 582, and 618 nm). High-resolution electron microscopy observations reveal that about 5% of the nanoparticles have a lattice structure, while the remaining nanoparticles are amorphous. Electron diffraction of the Y nanoparticles gives lattice spacings corresponding to the cubic structure of yttrium oxide (Y2O3). The most optimal dopant content for luminescence of Y:Eu and Y:Tb nanoparticles in apoferritin cavity are about 60% and 40%, respectively.

  8. Mycosynthesis of silver nanoparticles bearing antibacterial activity

    PubMed Central

    Azmath, Pasha; Baker, Syed; Rakshith, Devaraju; Satish, Sreedharamurthy

    2015-01-01

    Mycosynthesis of silver nanoparticles was achieved by endophytic Colletotrichum sp. ALF2-6 inhabiting Andrographis paniculata. Well dispersed nanoparticles were characterized using UV–Visible spectrometry with maximum absorption conferring at 420 nm. FTIR analysis revealed possible biomolecules reducing the metal salt and stabilization of nanoparticles. XRD analysis depicted the diffraction intensities exhibiting between 20 and 80 °C at 2theta angle thus conferring the crystalline nature of nanoparticles. Morphological characteristic using TEM revealed the polydispersity of nanoparticles with size ranging from 20 to 50 nm. Synthesized nanoparticles exhibited bactericidal activity against selected human pathogens. Nanoparticles mode of action was carried out to reveal DNA damage activity. Thus the present investigation reports facile fabrication of silver nanoparticles from endophytic fungi. PMID:27013906

  9. Physical Principles of Nanoparticle Cellular Endocytosis.

    PubMed

    Zhang, Sulin; Gao, Huajian; Bao, Gang

    2015-09-22

    This review article focuses on the physiochemical mechanisms underlying nanoparticle uptake into cells. When nanoparticles are in close vicinity to a cell, the interactions between the nanoparticles and the cell membrane generate forces from different origins. This leads to the membrane wrapping of the nanoparticles followed by cellular uptake. This article discusses how the kinetics, energetics, and forces are related to these interactions and dependent on the size, shape, and stiffness of nanoparticles, the biomechanical properties of the cell membrane, as well as the local environment of the cells. The discussed fundamental principles of the physiochemical causes for nanoparticle-cell interaction may guide new studies of nanoparticle endocytosis and lead to better strategies to design nanoparticle-based approaches for biomedical applications.

  10. Endotoxin hitchhiking on polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Donnell, Mason L.; Lyon, Andrew J.; Mormile, Melanie R.; Barua, Sutapa

    2016-07-01

    The control of microbial infections is critical for the preparation of biological media including water to prevent lethal septic shock. Sepsis is one of the leading causes of death in the United States. More than half a million patients suffer from sepsis every year. Both gram-positive and gram-negative bacteria are responsible for septic infection by the most common organisms i.e., Escherichia coli and Pseuodomonas aeruginosa. The bacterial cell membrane releases negatively charged endotoxins upon death and enzymatic destruction, which stimulate antigenic response in humans to gram-negative infections. Several methods including distillation, ethylene oxide treatment, filtration and irradiation have been employed to remove endotoxins from contaminated samples, however, the reduction efficiency remains low, and presents a challenge. Polymer nanoparticles can be used to overcome the current inability to effectively sequester endotoxins from water. This process is termed endotoxin hitchhiking. The binding of endotoxin on polymer nanoparticles via electrostatic and hydrophobic interactions offers efficient removal from water. However, the effect of polymer nanoparticles and its surface areas has not been investigated for removal of endotoxins. Poly(ε-caprolactone) (PCL) polymer was tested for its ability to effectively bind and remove endotoxins from water. By employing a simple one-step phase separation technique, we were able to synthesize PCL nanoparticles of 398.3 ± 95.13 nm size and a polydispersity index of 0.2. PCL nanoparticles showed ∼78.8% endotoxin removal efficiency, the equivalent of 3.9 × 105 endotoxin units (EU) per ml. This is 8.34-fold more effective than that reported for commercially available membranes. Transmission electron microscopic images confirmed binding of multiple endotoxins to the nanoparticle surface. The concept of using nanoparticles may be applicable not only to eliminate gram-negative bacteria, but also for any gram

  11. Dynamic Nanoparticles Assemblies

    PubMed Central

    WANG, LIBING; XU, LIGUANG; KUANG, HUA; XU, CHUANLAI; KOTOV, NICHOLAS A.

    2012-01-01

    CONSPECTUS Importance Although nanoparticle (NP) assemblies are at the beginning of their development, their unique geometrical shapes and media-responsive optical, electronic and magnetic properties have attracted significant interest. Nanoscale assembly bridges multiple sizes of materials: individual nanoparticles, discrete molecule-like or virus-like nanoscale agglomerates, microscale devices, and macroscale materials. The capacity to self-assemble can greatly facilitate the integration of nanotechnology with other technologies and, in particular, with microscale fabrication. In this Account, we describe developments in the emerging field of dynamic NP assemblies, which are spontaneously formed superstructures containing more than two inorganic nanoscale particles that display ability to change their geometrical, physical, chemical, and other attributes. In many ways, dynamic assemblies can represent a bottleneck in the ‘bottom-up’ fabrication of NP-based devices because they can produce a much greater variety of assemblies, but they also provide a convenient tool for variation of geometries and dimensions of nanoparticle assemblies. Classification Superstructures of NPs (and those held together by similar intrinsic forces) are classified into two groups: Class 1 where media and external fields can alter shape, conformation, and order of stable superstructures with a nearly constant number same. The future development of successful dynamic assemblies requires understanding the equilibrium in dynamic NP systems. The dynamic nature of Class 1 assemblies is associated with the equilibrium between different conformations of a superstructure and is comparable to the isomerization in classical chemistry. Class 2 assemblies involve the formation and/or breakage of linkages between the NPs, which is analogous to the classical chemical equilibrium for the formation of a molecule from atoms. Finer classification of NP assemblies in accord with established conventions

  12. Glyco-gold nanoparticles: synthesis and applications

    PubMed Central

    Compostella, Federica; Pitirollo, Olimpia; Silvestri, Alessandro

    2017-01-01

    Glyco-gold nanoparticles combine in a single entity the peculiar properties of gold nanoparticles with the biological activity of carbohydrates. The result is an exciting nanosystem, able to mimic the natural multivalent presentation of saccharide moieties and to exploit the peculiar optical properties of the metallic core. In this review, we present recent advances on glyco-gold nanoparticle applications in different biological fields, highlighting the key parameters which inspire the glyco nanoparticle design. PMID:28684980

  13. Alloy nanoparticle synthesis using ionizing radiation

    DOEpatents

    Nenoff, Tina M [Sandia Park, NM; Powers, Dana A [Albuquerque, NM; Zhang, Zhenyuan [Durham, NC

    2011-08-16

    A method of forming stable nanoparticles comprising substantially uniform alloys of metals. A high dose of ionizing radiation is used to generate high concentrations of solvated electrons and optionally radical reducing species that rapidly reduce a mixture of metal ion source species to form alloy nanoparticles. The method can make uniform alloy nanoparticles from normally immiscible metals by overcoming the thermodynamic limitations that would preferentially produce core-shell nanoparticles.

  14. Cobalt-substituted magnetite nanoparticles and their assembly into ferrimagnetic nanoparticle arrays.

    PubMed

    Yu, Yongsheng; Mendoza-Garcia, Adriana; Ning, Bo; Sun, Shouheng

    2013-06-11

    A simple process to prepare monodisperse ferrimagnetic cobalt-substituted magnetite Co(x)Fe(3-x)O4 nanoparticles is reported. These ferrimagnetic nanoparticles are readily dispersed in hexane, forming a stable ferrimagnetic nanoparticle dispersion, and allowing easy nanoparticle self-assembly. When assembled under an external magnetic field (5.5 kOe), these nanoparticles show preferred magnetic alignment with their H(c) reaching 2.49 kOe.

  15. Optical trapping of nanoparticles.

    PubMed

    Bergeron, Jarrah; Zehtabi-Oskuie, Ana; Ghaffari, Saeedeh; Pang, Yuanjie; Gordon, Reuven

    2013-01-15

    Optical trapping is a technique for immobilizing and manipulating small objects in a gentle way using light, and it has been widely applied in trapping and manipulating small biological particles. Ashkin and co-workers first demonstrated optical tweezers using a single focused beam. The single beam trap can be described accurately using the perturbative gradient force formulation in the case of small Rayleigh regime particles. In the perturbative regime, the optical power required for trapping a particle scales as the inverse fourth power of the particle size. High optical powers can damage dielectric particles and cause heating. For instance, trapped latex spheres of 109 nm in diameter were destroyed by a 15 mW beam in 25 sec, which has serious implications for biological matter. A self-induced back-action (SIBA) optical trapping was proposed to trap 50 nm polystyrene spheres in the non-perturbative regime. In a non-perturbative regime, even a small particle with little permittivity contrast to the background can influence significantly the ambient electromagnetic field and induce a large optical force. As a particle enters an illuminated aperture, light transmission increases dramatically because of dielectric loading. If the particle attempts to leave the aperture, decreased transmission causes a change in momentum outwards from the hole and, by Newton's Third Law, results in a force on the particle inwards into the hole, trapping the particle. The light transmission can be monitored; hence, the trap can become a sensor. The SIBA trapping technique can be further improved by using a double-nanohole structure. The double-nanohole structure has been shown to give a strong local field enhancement. Between the two sharp tips of the double-nanohole, a small particle can cause a large change in optical transmission, thereby inducing a large optical force. As a result, smaller nanoparticles can be trapped, such as 12 nm silicate spheres and 3.4 nm hydrodynamic radius

  16. [Magnetic nanoparticles and intracellular delivery of biopolymers].

    PubMed

    Kornev, A A; Dubina, M V

    2014-03-01

    The basic methods of intracellular delivery of biopolymers are present in this review. The structure and synthesis of magnetic nanoparticles, their stabilizing surfactants are described. The examples of the interaction of nanoparticles with biopolymers such as nucleic acids and proteins are considered. The final part of the review is devoted to problems physiology and biocompatibility of magnetic nanoparticles.

  17. Nanoparticles for Imaging: Top or Flop?

    PubMed Central

    Mertens, Marianne E.; Grimm, Jan; Lammers, Twan

    2014-01-01

    Nanoparticles are frequently suggested as diagnostic agents. However, except for iron oxide nanoparticles, diagnostic nanoparticles have been barely incorporated into clinical use so far. This is predominantly due to difficulties in achieving acceptable pharmacokinetic properties and reproducible particle uniformity as well as to concerns about toxicity, biodegradation, and elimination. Reasonable indications for the clinical utilization of nanoparticles should consider their biologic behavior. For example, many nanoparticles are taken up by macrophages and accumulate in macrophage-rich tissues. Thus, they can be used to provide contrast in liver, spleen, lymph nodes, and inflammatory lesions (eg, atherosclerotic plaques). Furthermore, cells can be efficiently labeled with nanoparticles, enabling the localization of implanted (stem) cells and tissue-engineered grafts as well as in vivo migration studies of cells. The potential of using nanoparticles for molecular imaging is compromised because their pharmacokinetic properties are difficult to control. Ideal targets for nanoparticles are localized on the endothelial luminal surface, whereas targeted nanoparticle delivery to extravascular structures is often limited and difficult to separate from an underlying enhanced permeability and retention (EPR) effect. The majority of clinically used nanoparticle-based drug delivery systems are based on the EPR effect, and, for their more personalized use, imaging markers can be incorporated to monitor biodistribution, target site accumulation, drug release, and treatment efficacy. In conclusion, although nanoparticles are not always the right choice for molecular imaging (because smaller or larger molecules might provide more specific information), there are other diagnostic and theranostic applications for which nanoparticles hold substantial clinical potential. PMID:25247562

  18. Nanoparticle confinement by the linear Paul trap

    NASA Astrophysics Data System (ADS)

    Lapitsky, D. S.; Filinov, V. S.; Syrovatka, R. A.; Vladimirov, V. I.; Vasilyak, L. M.; Pecherkin, V. Ya; Deputatova, L. V.

    2016-11-01

    In this article, the possibility of nanoparticle confinement by electrodynamic Paul trap is shown. The areas of nanoparticle confinement as the dependencies of particle charge density on voltage frequency and geometry of the trap are found. The nanoparticle charge density for its confinement should be of order (1013-1014)e/m2.

  19. Lactobacillus assisted synthesis of titanium nanoparticles

    NASA Astrophysics Data System (ADS)

    Prasad, K.; Jha, Anal K.; Kulkarni, A. R.

    2007-05-01

    An eco-friendly lactobacillus sp. (microbe) assisted synthesis of titanium nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ti nanoparticles. Individual nanoparticles as well as a number of aggregates almost spherical in shape having a size of 40 60 nm are found.

  20. Polymer Diffusion in the Presence of Nanoparticles

    NASA Astrophysics Data System (ADS)

    Winey, Karen

    2014-03-01

    The center-of-mass diffusion of polymers within a polymer melt proceeds by the mechanism of reptation wherein the polymer is confined to a tube that is defined by neighboring entanglements and moves along its contour. Polymer diffusion is perturbed when the melt contains nanoparticles that are comparable in size to the radius of gyration (Rg) of the polymers. Within this talk, we will present tracer diffusion coefficients (D) results for three types of nanocomposite: spherical nanoparticles with surface functionalization, spherical nanoparticles with brushes, and cylindrical nanoparticles (aspect ratio = 5 to 50). When functionalized spherical nanoparticles have neutral or attractive interactions with the polymer matrix, a monotonic decrease in the diffusion coefficient is observed across a wide range of polymer molecular weight, nanoparticle size, and nanoparticle concentration. These data collapse onto a master curve when plotted as D normalized by the diffusion coefficient into a neat homopolymer (D/Do) versus our confinement parameter defined as the interparticle distance divided by 2Rg (ID/2Rg). Polymer diffusion in systems with grafted spherical nanoparticles exhibit the same D/Do versus ID/2Rg, when ID accounts for the extent to which the tracer polymer penetrates the polymer brush. For various cylindrical nanoparticles D/Do versus nanoparticle concentration exhibits a minimum when 2Rg is both larger than the nanoparticle diameter and smaller than the nanoparticle length. Complimentary molecular dynamics simulations and neutron scattering results will also be presented.